I'm British, living in the UK, and having been through our own versions of this: disbelief that a majority voted for Brexit and years of Conservative governments, I've come to the conclusion that the majority of people vote according to their short-sighted personal financial concerns.
I don't think the Democrats could ever have won this time, because of the economic effects of Covid and Russia's invasion of Ukraine. I am sad that many people are so short sighted and narrow in their perspective, when as humans we so desperately need to be learning from the past, looking at the big picture and looking far ahead.
I'm offering this opinion to hopefully help you not waste time and effort wondering where the campaign went wrong, rather have confidence that without the campaign, the election results would have been much worse.
The tides will shift again, soon enough. So the Democratic party needs to be ready to catch the wave when it comes, when the majority of people want an alternative to Trumpism. But even then many people will only be voting Democrat because they believe it's in their own short term economic interests to do so.
This is the reality in the face of which we live and work, and yet that reality also includes those of like mind, those we connect with, to manifest love and truth in this world we all share.