The idea that it "should work" is both controversial, and doesn't help. As wealth accumulates at the top, they have less reason to give to anyone else. Human greed is encouraged by capitalism, and you end up with massive inequality when it's left unfettered. We're moving towards having robber barons again (or already do, depending on your viewpoint).
Not to mention, capitalism depends on consumption, of everything, and we are actively consuming the things we need in order for us to continue living on the planet. Capitalism doesn't care because it's all about profit, specifically in the short term because humans have short life spans and shorter memory and foresight.
Star Whores is a masterpiece, don't disparage it