Only 17% of American physicians are members. I quit them long ago, over their politics. Like so many foundations and non-profits in America, they were hijacked by Lefties years ago.
The antipathy of physicians for the AMA is not just about money, turf, and guild. It goes way beyond that. However, apparently the AMA's strenuous support of Obamacare (seemingly without understanding any of its implications) has been the final straw.
There is a new breed of young physicians, especially women, who don't mind being employees, having bosses, or working as an agent of the government, but most docs over 40 are not interested in that. In general, docs like autonomy, flexibility, self-direction. Also, they hate paperwork and bureaucracy.