Those folks are paying their time into the game sure - but casual games in IAPs can drain bank accounts surprisingly fast from folks that'd normally consider themselves above microtransactions. There is a lot of very sneaky psychological tricks that go into trying to get folks to spend an insane amount of money - I'd compare that to something like CS:GO which is trying to get everyone to spend a little bit of money but is less oriented to harness big spenders outside of the marketplace which isn't all that promoted in game.