Generally you can gain a pretty good understanding of how long the entertainment will last. Maybe not down to the millisecond, but you know a spin on the one arm bandit won't take hours. It will give on the order of seconds. Your willingness to give up x is contingent on the perceived entertainment value of those seconds. If you choose to play again, that is an independent event — like deciding to watch a second movie while you are already at the theatre.

> while secretly hoping that they'll actually leave with more than they came with.

Yes, this may be the undefined variable. The dopamine hit of believing you can come home better than you started, with little tastes of the possibility, coupled with loss aversion when it isn't being realized. This is what earlier comments seem to be speaking about, so perhaps, despite your insistence, a consensus was already reached.