Money this game makes

[kaynide]

Come on now, that's not a valid analogy and you know it. Every video game at the time was a physical, stand-alone product that had no way of being updated, patched, or expanded. Final Fantasy wasn't even an established series at that point, just an experimental game they didn't know would be a success or not. Making Final Fantasy II at all was as much "making more Final Fantasy 1" as anyone could have expected, so it shows the original game was profitable enough that Square saw fit to invest in more of "that," whatever they thought "that" was at the time.

I don’t see how it isn’t. Even current gen MMOs don’t necessarily put all their money back into the game.

You think Hearthstone, Diablo 3 or the Warcraft movie weren’t paid for by WoW?
Even non-MMOs, like Ark Survival Evolved, pour their profits into other projects like a sequel and an animated series.