Capitalism is the natural way to resolve a coincidence of wants & as such capitalism exists even when communism is imposed. 

Capitalism has a funny dualism with communism in that pure communism can never be achieved, while pure capitalism can only ever be suppressed. It's ironic that the virtuous goals of communism seem to be only achievable via capitalism & voluntarism. It's only through selfishly pursuing our own goals in a system with aligned incentives that all humans are able to thrive. 

 Now do corporatism which is what we’ve lived under our entire lives. 
Capitalism is science fiction. 

 Not science fiction. Elements of capitalism exist under what you call corporatism, it's just suppressed via fiat currencies & govt in general.

Capitalism existed where governments didn't exist or were very small. It's been a long time since we had free markets & pure capitalism at scale.