Literally first paragraph from his bio in wiki:

Javier Gerardo Milei[note 1] (born 22 October 1970) is an Argentine politician and economist serving as the president of Argentina since December 2023. Milei has taught university courses in macroeconomics, economic growth, microeconomics, and mathematics for economists. He has written numerous books on economics and politics, and also hosted radio programs on the subject.

As we can see he's basically accomplished veteran of all levels of economics. And regardless of capitalist economics being more or less worthless scam, there are countries run by it and not having nosedive into fascism and slavery in a week. Therefore we can assume that either he faked his entire career and nobody noticed that or he is doing what he's doing completely on purpose.