Ultimately the failure of Capitalism is starkly depicted by one thing. If one person, yes, only one, who wants a job but is denied one or there is none, then Capitalism has failed.

The moment one person, yes, singular, is laid off, then capitalism has failed.

This aside, Capitalism is the best system devised so far by humans. It feeds the inherent greed of human kind and so is perpetuated by human kind. Socialism does not, or is not supposed to, feed the greed. Where ever Socialism is instituted it is fought. Socialism can only exist where there is a dictatorship, or, if you imagine an unreal scenario, where there are perfect people.