Idle game players: what makes you quit an incremental game?

Cash Empire Clicker launches here on 6 November. I'm one of the makers.

It's a free idle tycoon game for iPhone and iPad: tap to print (fictional) cash, research upgrades, hire managers, automate and prestige. The 1.3 update rebalanced the whole economy so it plays like the classic incrementals: costs rise with every purchase, and reaching the top stages takes days, not minutes. It also added a Research Lab, three skill mini-games with rewards shown before you play, and office themes you unlock by playing.

A question for anyone who has sunk weeks into Cookie Clicker, Adventure Capitalist or similar: what's the moment you usually stop playing? A wall where progress stalls, prestige that feels like starting over, ads, something else? I read every reply.