Stress
If you really hate numbers or math gives you the shakes, this isn't going to work out for you. You have to be able to crunch digits (using more than just fingers and toes) and communicate the results to your customers, whether they're in front of your face, gathered in the same building, or spread across the world on a 21st century network of shut-ins with money to burn.
Legal and financial issues can also come into play. Gambling is one of those less, shall we say, "Church Lady-approved" pastimes that people of all stripes engage in. Some people do attempt to block it through legal means, either locally or at the state level. If the law changes, you need to know it, because the bets made from prison aren't redeemable, generally speaking.
Further, let's not forget that this is a business where millions of dollars can be lost in the blink of an eye. So there's the added stress of imminent financial ruin (okay, maybe it's not that dire). And unlike banks or Wall Street firms, Uncle Sam probably isn't going to want to bail you out.
You also have to be able to deal with people, because you'll be dealing with them a lot. Some people go all-in and when they lose they lose big. When they lose their minds afterwards, they often do it in your direction. That's why it's important to read the gambling room, so you know whose chips are up and whose are down.
Basically, the take-away is there's no shortage of stressors when dealing with gambling.