Better for him to stop gambling completely because he may get the same experience in other casinos sooner or later, sorry to say but as gambler we should be ready for all the worse possible case.
In fact he is not the only one with such experience in gambling especially in slot games, I have myself experienced my worst result on slot few years ago when bonus buy on slot game was starting to be popular.
When many people shared their luck on it, I keep on trying but no luck for me and I lost much money as well with several bad losing streak as well.
Did I call the casino as scam? Of course not because I cant prove it and I cant accuse a casino as scam just because I lose some money.
Luck changed, there were also some time when I won significant amount and multiplier on slot game as I shared mostly in the Slots 101 thread.