Isn't gambling all about that? This player had a great luck to win that amount of money in exchange of only 50$ which is very little compared to what he won. Personally, I would have done the same thing if I got the same chance he had. However, in these cases the chances are very low but the prize is very tempting.
If we talk about the amounts of money we spend on gambling, slots, sport betting and other games... we are risking way more money without noticing it. I had many good winnings while gambling and I don't regret taking the risks of what I'm doing every time I bet either winning or losing still we should be responsible of what we are doing and spending this money we can afford losing.
In the other side, some people consider 50$ as a big some of money to spend in gambling in one hit, knowing that the risks of losing it are very high. So I think it depends on how much you are willing to spend and afford. Never gamble what you can't afford losing
A bet like that is not much of a problem as long as it is not a bet that you make regularly, after all even if 50 dollars may not seem like a lot of money, if you began to make several bets like that then the money you will lose will grow significantly, still the story on the OP is a nice example of what gambling is about, as there is probably no other activity on the world which can give you 42 millions by just risking 50 dollars on a single spin.