Capitalism seems to be a fairly successful economic system when it's tried, in the sense that it seems to be pretty good at producing economic growth. It has a few powerful enemies. As Adam Smith pointed out in his seminal book, nobody hates a free market like the capitalists who have to compete in it, and since successful capitalists get a lot of money and concomitant political power, they work like crazy to shut down competition. Fascism, crony capitalism and oligarchical kleptocracies are a common result. Every once in a while, oligarchies get so inefficient and cumbersome that they trigger a successful revolution.
That's the fate that the hysterics on the anti-left would lead us to. Those who see Communists under every bed and in every closet would turn the nation over authoritarian minded would be fascists like Trump.