Don't be afraid he will lose it since he know what do to with his money. Risking $15 each bet in slot just need 1000x times roll and it doesn't even take a day to complete it. That's why people like from slot games, sometimes you can unexpected profit from your small bets, i've seen many people got really lucky on slot games through youtube.
Indeed, in a slot game like that we can only complete hours of bets with 1000x rolls even if it's lucky I believe in strong belief with a $ 15 bet even this has happened a lot with 1000x rolls more so obviously their profits are huge in general slots are always giving an unexpected win as well as other bets in my opinion.
Whatever I see on YouTube or in other slots are now being played a lot, because indeed with big wins.