Probably helps that the core devs are in Argentina IIRC. They don't need to pay themselves as much as developers in the states or western Europe (though hopefully their compensation is still more than adequate).
A bit like LibreOffice, actually - donation-sustained, ecosystem includes commercial companies which use the tech with modifications/extensions, who donate money, new features, bug fixes etc.
https://www.numbeo.com/cost-of-living/country_result.jsp?cou...