“ The definition of racism is very clear — prejudice, discrimination, or antagonism directed…
Al Black

What consistently baffles me is that there is no restriction on who can think himself or herself superior. So why can’t black people ever wake up one morning and think to themselves “From today, I’m superior to the white man”. What is this invisible hand holding back other races from getting into this superiority game and why are whites the only ones allowed to have monopoly on thinking themselves superior.

The answer is simply that as you say, superiority in any form believed or not believed by oneself, real or imagined, has nothing to do with discrimination, prejudice or antagonism. Discrimination or prejudice are the problem not whoever thinks himself superior. It might be an excuse but is not intrinsic to racism or any other ism for that matter.

The nonsensical concept being pushed is therefore that any minority group can simply assume or impute upon anyone they don’t like a title of “superior to us” even if you don’t think you are and thus you become complicit in their imagined marginalization. If only any of it actually helped actually marginalized folk but academia isn’t interested in solving the problem just theorizing endlessly about it.