in short, argetina took some big ass loans to imf during their military dictatorship, so they are in a permanent crises since that.
Funny enough, Nestor Kirchner did pay most of the loans. And that made the right and the Argentine elite really angry since their entire thing was not doing anything good and when people complained they would say that "Oh, it's because of the loans we took. We can't do anything besides neoliberal reforms".
Then Macri decided to take more loans, and Alberto decided to actually attempting to pay the loans when they should have told the IMF to go fuck themselfs.
Latin america is still very anti-communist, so if you run a campaign blaming everything on the leftists, you are going to be popular. It really do be as simple as that, milei just screams stupid incoherent shit and blames the left thats his whole thing.
There were mass murders of leftists throughtout all latin america and its a wound that it is still bleeding.