It's not even bread and circuses. I mean, that's part of it, but raw consumerism isn't quite enough to stifle politics. You've also got patriotism aligning the most energetic and emotional potential reformers with the state itself. You've got an economy that's struck the perfect balance between exhausting the workforce without driving them to resentment - so much so that people still think jobs are an objectively good thing. You've got a glut of cheap addictions to keep people pacified during their downtime, and moreover a lot of them have become interactive enough to satisfy the drive to achieve without risking any real change. The economy's also debt-focused, netting people down with constant obligations to the system.
It's not just that it's comfortable. It's that almost every simple drive humans have has been channeled into maintaining the status quo. The cross section of people who have the motivation, the skill, the wealth, the energy, and the time to do anything is miniscule.
There will not be a forcible American revolution for the foreseeable future. To hope for it is to put your faith in a dramatic phantom. There is no justice here, and there never will be. The best we can hope for is to make it a little more profitable to actually make the world a better place.
EDIT: Oh, yeah, and the whole prisons thing! There's another thing slicing out a segment of society that's not content with the status quo, for whatever reason.