If George Washington declared himself king, you might be looking today at 30% unemployment like some of the euros
So I sometimes try to avoid mentioning it, and especially anything to do with Brit royalty.
Still, the UK is objectively doing alright these days, and objectively has a monarchy :)
I dont think you can qualify government as "just one small part". America would not be in the same place today without the decisions taken over time by its leaders. The same decisions would not be made under a different system of incentives for a leader like a monarchy/anarchy