You're citing my text but cutting off just before the point I was trying to make.

Yes, because my point is that your point doesn't make sense.

I think be would still side with the people who claim to follow his ideology

Why...? That's not how leftwing politics worked, ever, and it's not like there has ever been a shortage of leftwing criticism of Leninism and Stalinism.

r in Marx's case admitting that his ideas didn't work or the fact that they didn't work as intended cost the lives of millions.

Yeah that's my point: They're not his ideas; they're their ideas. Lenin for example, aside from being an authoritarian dickhead, was an intellectual juggernaut and a lot of his ideas would be baked into the foundation of the Soviet Union. There's simply nothing to support what you're saying.