I mean... df literally wasn't for sale until recently. They only monetized because American healthcare is bananas (its mentioned in this article and discussed more fully earlier https://www.pcgamer.com/if-dwarf-fortress-sells-millions-on-...). Otherwise it sounds like they would've been content with the ongoing patreon funding they had. It was quite popular before the graphics version.
It's true, Tarn and Zach are very committed to their art. It's really impressive and inspirational, truly, and I'm happy for their success -- both critical and financial.
Personally, I'm willing to make sacrifices to make games, but I'm not willing to go as far as them.
