> Capitalists claim that this is optimal

That's not what capitalists claim. Capitalists claim communism is responsible for tens, if not hundreds, of millions of death due to famine. And overall miserable ways of life, as if humans were termites deprived of any individualism and any freedom.

Capitalists claim that France importing 500 000 people from the third world each year, out of which only 10% are ever going to work (and these are official numbers) and yet offering them all a safety net is unsustainable. And that that socialism is only going to lead to one thing: running out of taxpayers' money.

Capitalists don't claim they have the best system: what they claim is that they haven't seen a less worse one.