I believe in socialism, but I feel Stalin shouldn't be idolised due to things like the Gulag.
I would like more people to become socialist, but I feel not condemning Stalin doesn't help the cause.
I've tried to have a constructieve conversation about this, but I basically get angry comments calling me stupid for believing he did atrocious things.
That's not how you win someone over.
I struggle to believe the Gulag etc. Never happened, and if it happened I firmly believe Stalin should be condemned.
No one has referred to capitalism as efficient or entirely rational.
We are referring to the incentive structure that the capitalist mode of production creates, and which behaviors that structure rewards and therefore elevates into positions of authority.
The framework you are describing as the foundation for your analysis sounds very analogous to the anarchist concept of "authoritarian personality disorder," and I personally don't find that to be a very rigorous or intellectually sound framework for understanding the world. To the contrary, it is an unfalsifiable orthodoxy. You are basically starting from an assumption of ill intent, and therefore any evidence that is presented is transformed into evidence of malice by speculating on internal and inherently unknowable "bad thoughts."
It's an entirely unscientific way of trying to understand the world.