Michael Kinsley (via Ben Smith) relates a story about McCain losing it at a craps table in Puerto Rico in 2005:
"McCain immediately turned to the woman and said between clenched teeth: ‘DON’T TOUCH ME.’ The woman started to explain...McCain interrupted her: ‘DON’T TOUCH ME,’ he repeated viciously. The woman again tried to explain. ‘DO YOU KNOW WHO I AM? DO YOU KNOW WHO YOU’RE TALKING TO?’ McCain continued, his voice rising and his hands now raised in the ‘bring it on’ position. He was red-faced. By this time all the action at the table had stopped. I was completely shocked. McCain had totally lost it, and in the space of about ten seconds. ‘Sir, you must be courteous to the other players at the table,’ the pit boss said to McCain. "DO YOU KNOW WHO I AM? ASK ANYBODY AROUND HERE WHO I AM."
You know, even though Kinsley relates this story secondhand, I have absolutely no doubt that it's true. Given McCain's childish behavior in the debates and in his public appearances, it's no stretch to think that he would react like Tony Soprano to a perceived slight. As Kinsley points out, his temper is a bit of a settled issue; everyone has heard the stories of his outbursts, his propensity for lashing out even at those in his caucus, the quickness to anger directed even at his own wife.
It's the sheer arrogance illustrated here that gives this account a new wrinkle. "DO YOU KNOW WHO I AM?" You expect to hear that from some over-pampered celebrity, but not from a U.S. Senator, someone whom you'd expect to behave with a modicum of restraint and decorum towards others. That he'd say such a thing, and with such a slight provocation, really is indicative of a sense of entitlement, and it really drives home the notion that McCain really does think he's better than everyone else.
Given all this, it's actually pretty easy to understand why McCain would resort to his current tactics. He's the best, and anything it takes for him to assume his rightful place as President is fair game. After all, don't you know who he is?