Disagree. The more disparity in wealth there is, the more anti-democratic. There are many small towns in the U.S. that are captured by a single large employer (who I guess is a “little rich”) through threats to move or lay-off workers, campaigning, “donations,” or just straight-up kickbacks to judges and law enforcement.
Capitalism is inherently anti-democratic. It creates an owner class and a worker class, and the owner class has a very large amount of power over the worker class. Something like a worker cooperative is inherently democratic (workers own and control their workplace/means-of-production, democratically).
As for “successful,” I suppose that depends on what metrics you use. I’d bet there have been other societies that were on a whole happier than capitalist industrial societies. I think we can do better than capitalism, and I think the survival of the human species depends on it. Capitalism requires unending growth to function, and I don’t think that’s sustainable on a planet with finite resources and a finite atmosphere that can only take so much greenhouse gasses being dumped in it before it causes a reduction in other resources, such as arable land.