This discussion has already happened hundreds of times. I'll say that Mao and Stalin are leftists that killed way more than Hitler. And you'll say they aren't really leftists.

The problem with these radical solutions is that they are ultimately unscientific. There's nothing you can say to a feminist that will convince them that wars aren't caused by toxic masculinity. Nothing you can say to a leftist that will convince them that horrors of capitalism don't outweigh the benefits.

At the end it comes to this: you can practice socialism in a capitalistic society. But you can't practice capitalism in a socialistic one.