Which revolutions in the 1900s were started for fun? Unless you're considering CIA backed coups in that count?

Loads, the various attempts to overthrow the Weimar Republic for one, but many smaller, like the Impresa di Fiume.

Maybe not “for fun” but largely for justifications that pale in comparison to the suffering they unleashed.

Americans ready to go to war because eggs and gas are too expensive, or their trans teen’s top surgery was delayed, might be making similar mistakes. But Americans are good at making mistakes, perhaps supernaturally gifted.