People tend to hate on greatness, They are historically the best team in baseball. Some people think that the Yankees are basically trying to "BUY" the championship by finding loopholes to be able to keep such high paid players.
I can't stand the Yankees myself, but as NAFTA said the do try to buy the world series every year. They are a good team and have been around forever, some see them as tradition,greatness, or a buy-a-ring team. I can't say too much because my team is horrible, the Astros. Or as I have been calling them lately the LAstros, since there are always in last place.
The fact that they are a team of mercenaries and wouldn't be squat without their owners checkbook is a good reason to hate the Yanks but is really just the tip of the iceberg. That being said, the Yankee fans are a large reason why. They are arrogant, boo their own superstars and worst of all are ignorant when it comes to the rest of MLB. Yankee fans are like spoiled brats that whine when they can't have what they want. Who boo's a future hall of famer like A-Rod when he's your best player? The Fans and media in New York actually make it more difficult for their own team to win by putting more pressure on them. They think that all that matters in the baseball world is the East Coast. Which is ridiculous. There are plenty of great baseball towns with lots of rich tradition in this country that don't reside on the east coast. Oh and by the way, AL ball is not real baseball. Lose the DH!!!