I can't really tell you how communists think, to be honest, because I am not exactly one. It's a weird thing (in the US?) that everyone who is not libertarian is considered communist (and not any communist: mostly the kind that is "the enemy" in cold war era video games, apparently).
There are many systems that would probably be considered communist in the US (at least by those of you who seem to have no clue about anything that is not libertarian) that work really well without genocides. But you'd have to open a book that is not US-centered to see that.
I'm not American, nor am I a libertarian. I'm a socialist Arab.
I still object to communism, and populist memes like "eat the rich." At best they're immature, at worst they're agents of chaos and destruction who actually harm the lives of millions when they get what they want.
There are many systems that would probably be considered communist in the US (at least by those of you who seem to have no clue about anything that is not libertarian) that work really well without genocides. But you'd have to open a book that is not US-centered to see that.