One hypothesis is that they haven’t yet suffered directly from the financial/economic crisis, or that they don’t believe the plan will prevent things from getting worse.
Another is that, at least for the moment, self-interest is outweighed by considerations of (perceived) fairness, including revenge. So argues Dan Ariely.
Lane Kenworthy 
Ariely’s definitely spotted the core belief underlying the opposition to the bailout. I talk to more people than most about this (adjunct instructor in Economics) and the most common expression I hear is “Socialism for those guys, capitalism for me.”