Levistus's_Leviathan
5e Freelancer
No one is saying that it's unreasonable to assume that something like Dune or WH40K's fascist governments could exist in the future if/when we get access to more common space travel for humans from planet to planet, they're more saying that idolizing that idea and striving for that kind of future is wrong.This is as far into RL politics I will go, but even though WH and just about any dystopian world setting (the word dystopian might be a clue) are meant to be purely fantasy, perhaps cautionary tales (if the writer is really clever), RL is indeed heading down that path. I was reading an article (think it was Bloomberg) where the point was made that Musk now has more relative wealth that Carnegie did, before Standard Oil was broken up, and Carnegie started giving it all away. One only has to pick up a newspaper and read about the rise of authoritarianism across the planet.
It is not at all unreasonable to suggest that something along the lines of the Dune political system with House Musk, House Apple, House Bezos, et al will run humanity in the future. That is certainly a fascism-adjacent reality.
(And, yes, you are correct that the world's current class of billionaires and millionaires are have a ton of wealth. The wealth disparity between the working class and the billionaires is greater than it was in France before its Revolution.)