I was a sophomore in high school during the 2000 elections (jk, I was in Tanzania). Obviously, I didn't pay much attention to the GOP Primary but I do remember Bush and McCain being neck and neck. I came across a couple of videos from the GOP debates and McCain seemed like a very likeable guy. He was even on point about how Gov. Bush's "Bush Tax Cuts" would not be a great policy. Instead, he argued, the surplus money should be used to pay down the debt. Nowadays, he likens letting the Bush Tax Cuts to expire as to armageddon. What happened to McCain over all these years? During the 08 General Election and his 2010 Senate Campaign he was and still is a completely different guy. <iframe width="420" height="315" src="http://www.youtube.com/embed/xk0-bR3fwZo" frameborder="0" allowfullscreen></iframe>
I think of it as the Republican party even just as recent as 2000 wasn't as crazy as it is today. McCain simply ran towards crazy like most in his party.
Politicians are like racist football coaches in the early '70s. No matter what they believe, they still just want to win.
I think I agree with pouhe (even if his illustrations are odd). McCain had a marketing strategy in 2000 to be more centrist (and thus "electable") than Bush. It didn't work. Now, he isn't running for President any more and must direct his marketing to Arizona voters. Who knows what McCain or any poltician actually thinks is good policy. They probably don't even know. And maybe it's better that way anyway with politicians voting the way the slimmest majority wants him to regardless of what he might have thought as a private citizen.
He had to move right for his political career. Unfortunately, moderates don't typically do well in primaries.