Why not? Dictators often purge anyone who is a threat, often because they form a possibly competitive power structure (regardless of their intent), and often because of paranoid perceived disloyalty, and for actual disloyalty.

And corruption is the cover story they commonly use - it's vague, general, the public sees enough gov't corruption to believe it and to hate it. Trials are not needed. Off the top of my head, Putin in Russia, Mohammed bin Salman in Saudi Arabia, ...

That's not an "or" question, imo. If you threaten the king by having too much power, too many allies, or too keen a mind, you get moved off the board. Disloyalty and risk of disloyalty are both abhorrent to autocrats.