Salary caps are more about keeping smaller clubs competitive. Is it really the case here? I think if this guy's company was acquired for $1B and he made $250M from the sale, people wouldn't be surprised at all.

No you're right, capitalism would not do the same thing as a sports club because the sports club has the incentive to be fair.

Though we give ourselves a pass in the name of capitalism, we could also prioritise fairness in our societies.

ok maybe bat an eyelid,

but I dont see news articles about athletes in such negativity, citing their young age etc.

You must not follow sports very close. Every time a young supports signs his first big deal, people freak out and compare it to the last superstar's deal. "Young players getting too much money before they earned it" is a trope at this point.