If you begin with 5 apples and lose 2, how many have you got? Most adults without a severe learning disability will say they have 3 apples, but not everyone actually perceives it that way even if their arithmetic skills are perfectly adequate. To some people, beginning with 5 apples and losing 2 means they have negative 2 apples - their world is defined by loss from a continually-advancing baseline. What if you begin with 5 apples, gain 2, and then lose 1? Most people would consider this a net gain, but net only matters if your baseline is fixed: Since at some point you had 7 apples, the perspective of the negative mind is that you have lost an apple. This not only makes for unhappy people, but extraordinarily obnoxious, fear-driven, and weak-willed citizens.
The truly astonishing fact is that some people have a choice, and yet choose to view the world in these terms because it's easier: It takes far less energy to respond to a perceived absence - i.e., the failure of something in your mind to correspond to external reality - than to interact with the environment dynamically and be aware of what is there. No sentience is required for this mentality beyond the most basic - you have, want, or expect something, and it fails to be maintained or provided by the universe.
Now, this would be understandable if your baseline is something you never chose - e.g., how much food or water you need to survive. If you need 8 apples to survive, then starting with 5, gaining 2, and then losing 1 isn't negative 1 apples, it's negative 2. But even then there are arguments (such as in Buddhism) that your baseline is arbitrary, and that you would still be in nonzero territory if you died: You had lived, and most of what was you other than your perception of self is still there. But I won't belabor these abstract domains of philosophy - it's perfectly reasonable to be negative if you're ill, malnourished, dehydrated, or terrorized.
Unfortunately, negativity as a general attitude is a form of self-terrorism, and not exactly congenial to others either - it's a deliberate, false sense of desperation cultivated in the mistaken belief that it helps maintain advantages already won. The problem is that it emphasizes guarding what you already have, and is indifferent (or even hostile) to advancement - the "zero" condition simply moves forward, and you either fail to mark its movement or even resent the progress because it's harder to maintain (from a negative perspective) than a lower boundary. It's thus an inherently conservative approach to life, and ultimately a losing proposition because entropy is always taxing the status quo.
No great advancement in history has ever occurred because of people seeking to "regain lost glory." All such attempts result only in cargo cult mockeries of the past - people deluding themselves that they're recapturing something that is gone while forsaking the future. The actual Romans wouldn't have condescended to piss on the Holy Roman Empire - a ceremonial farce acted out by people with no conception of what allowed Rome to create the civilization whose power they venerated. When approached with awareness and honesty, history is a teacher, not a blueprint, and its heroes have bowed to you by necessity of time: You are on stage, not they.
True progress occurs because of awareness of what is, imagination of what could be, and the positive understanding that it begins whenever and wherever you choose - you need no one's permission, and there is no such thing as failure other than a choice to stop learning. But to make progress, you have to be willing to begin from where you actually are - the unstable reality of extant potential - not from where you wish to be or where you believe you were in the past.
Consider the two Presidents, Franklin Roosevelt and Ronald Reagan, who have become avatars of the respective presidential aspirations of the ideological left and right, despite their (conveniently forgotten) dissatisfaction with those leaders at the time. They may both have admired past Presidents, but neither lived in the shadow of a cargo cult - they responded to their environment according to their divergent natures, informed by their own perceptions, and brought about radical change as a result. In so doing, they generated their own cargo cults - the Zombie Reagan and Zombie FDR contingents on the right and left, respectively: People who want to recapture past glory, as they define it, because they see the present in negative terms.
That which defines a cargo cult is the confusion of form with substance - of superficial characteristics with underlying nature. It confuses drama with change, rhetoric with policy, action based on consciousness with cynicism: To walk around a wall rather than attempt to walk through it is somehow a failure of effort, or an act of cowardice. Political cargo cults do not recognize the irony of their existence - that they only imbue the objects of their reverence with such power because of accomplishments born of rejecting their own mentality. By necessity, such views will be wholly negative because their objectives are unattainable - to return to the past while maintaining the distance from it (and ignorance of its reality) that breeds their certainty in its perfection.
Anyone with healthy curiosity would like to visit the past, but wanting to live there or remake the present in its image is neurotic: Anyone who succeeded would immediately regret it, because from their own perspective they would still be living in a present that contains their insecurities. The same is true for people who use an imagined future as a baseline, and are perpetually judging all real work as inadequate and its architects as fools, cowards, or traitors.
What's more, they will resist admitting the adequacy of anything or anyone because they can't imagine satisfaction not yielding laziness - they view progress as having an objective rather than being the objective. Life, evolution, and freedom do not have destinations: There is no Promised Land other than the one you create on a daily basis. Your choices do not lead to Heaven or Hell, they are Heaven or Hell - and there is no stillness in either.
Either you joyfully blaze forward into the future, exploring and experiencing possibilities, or you wallow in illusions as your world falls around you. There are degrees, but you cannot avoid making the choice: Is progress discovery and motion, or is it a static quality of attainment and possession?
But don't misunderstand, negativity isn't a character flaw - it's a result of alienation. If you don't communicate with your environment or understand yourself, you're aware of much less, and thus it's a lot easier to "lose" things (i.e., lose sight of them) and not recognize that your very existence is something positive. The solution begins with self-awareness: You can't be aware of other people until you're aware of yourself, and you can't change the world until you know both yourself and it well enough to understand your mutual relationship and how it can change for the better.
These may be cliches represented throughout history in poetry, philosophy, and song, but they're true both in abstract and in practice. We can't always be positive - not unless one has an amazing level of psychological discipline - but we can keep our troubles in some kind of perspective even when we find them intensely irksome, enraging, or frightening.
It may be that a small minority of the people on Earth (i.e., white American men) had better prospects in life in 1965 than they do today, and it may be that some measures of prosperity for Americans as a whole are lower today than then, but this country didn't achieve those results in the post-War era by trying to restore an imagined heritage - that was the lament of conservatives who pined for the "golden age" of ragtime music and Boater hats.
Nor were those results achieved by people who wallowed in imagined future utopias: They may have offered ideas and inspiration to people who brought about practical advances, but those who couldn't reconcile themselves to humanity as it is - in other words, to their own limitations and insecurities - ended up as obscure, bitter ideologues perpetually shouting "J'accuse!" at everyone who came within a parsec of actual political authority. And the most unfortunate of all, whose vision of the perfect world was so powerful they couldn't love and work with the real one, ended up creating the exact opposite in Eastern Europe and Asia.
The miracles of this country were achieved by people who knew they were alive, and that what matters is the progress you make today in the world you inherit - not bowing at the altar of your ancestors' achievements or pining for a conceptual ideal. But even in giving those people their due credit, I'm not appealing to them - they're dead, and the record of their experiences is useful only for learning the context of the present, not mapping the way from a "here" that isn't here anymore to a "there" that isn't there anymore. I prefer to strive for my own navigation, charting a course between imagination and fact to avoid the traps of self-defeating ideology and self-enforcing fatalism. There is no other way to affect change: You start with where you are standing, and put one foot in front of the other. There is no teleportation in politics.