Thieves and scammers prefer fiat and Keynesian economics for the same reason they prefer shitcoins.

Interestingly enough, even Keynes recognized the destructive power of inflation: “There is no subtler, no surer means of overturning the existing basis of society than to debauch the currency. The process engages all the hidden forces of economic law on the side of destruction, and does it in a manner which not one man in a million is able to diagnose.” John Maynard Keynes [The Economic Consequences of the Peace]