He got four of a kind twice during a 30 minute poker run (Hold'em) and thought that having a Queen was the Bees Knees. He doubled up twice and left (smart) and swore he'd always play queens (which is whatever). What he never realized and it was apparent when I spoke to him was that the dealer was cutting the cards to give him a couple of good hands before soaking him for all he was worth. He left before getting soaked which was smart but it goes to show that you never play with a tourist attracting dealer (he was in Mexico).
That sounds like an expected loss. The scammer likely wins enough from the times it works, that it covers the few times someone walks early.
Most people don't walk immediately after winning big. The dopamine rush is difficult to resist. A few do, and if that scammer was a pro, I doubt your friend was his first loss, or will be more than his winnings from others.
Also a loss can sometimes be used to hook other fish.
Good play by your friend though. For many it's not easy to walk away on a peak.