Leftism at scale across diverse populations is a technological impossibility. The development and distribution of technology at scale is presently only possible through capitalism. Ultimately leftists have to choose: escape local maxima or be suicidally ethical.
There are a lot of places where I'm sympathetic to the left. How much of the human soul survives the coming centuries is at least as important as whether or not consciousness survives at all. We must remember the impossible, for the sake of the future when it is no longer so.