It's later, but as someone that has studied Bolivian economics, in short Bolivia took revenues from natural resources (hydrocarbons, lithium, other metals like copper) and use all of the proceeds only for investment spending: like building infrastructure, schools, hospitals shit like that. Then, he used regular taxation and the revenues not spent on investment to fund day-to-day spending, by doing this he was basically able to fuck with the curse of resources by using its income purely for more expansionary spending, in laymen's term converting petrodollars into investment that pays back more money longterm. Since he used direct taxes and the savings he made not using taxes on investment to fnud day-to-day spending, he was able to run a surplus.
That is very simplified, ignores shit like his "3 Rs" programme to combat adult literacy:
>Officials say that it is thanks to the "Yes, I can" programme that illiteracy rates dropped from 13.28% in 2001 to 3.8% in 2014, when the last census was conducted.
But yeah, in effect Morales hacked neokeynsianism and did some MMT-type shit (although not actual MMT).