While capitalism seems cruel and Darwinian (it is), no other economic system has raised so many people out of poverty, and socialism/communism has such a horrific track record that no serious person can even suggest that it might be successful on a broad scale. In a convent or monastery or a commune, maybe. But there, everyone is voluntarily associated.
The vaunted social democracies of Europe were founded on the economic success of capitalism, and simply bleed off some of the wealth to fund social programs. But like any Ponzi scheme, it requires more and more people paying in, to fund the social programs before they dry up and the nation goes bankrupt. So you see "leaders'" in Europe paying people to have babies, and encouraging massive immigration, hoping that the immigrants will work and pay taxes, rather than suck up social benefits and make the problem worse.
Capitalism does require some constraints, but socialism is a pipe dream.