While this might be the case for many of us, there is definitely a group of people who like risk and uncertainty. If you don't look for it you go for a safe 9 to 5 job without any upside. Your salary is fixed and you won't make any big pay jumps. People in the finance industry work a lot based on bonuses, so their salary is uncertain too. Or people working in sales are paid by commissions. There is also a change your salary per month.
Although both gamblers and employees get uncertain income, at least employees don't have the risk of losing money or the worst possibility is that what they did doesn't get rewarded, so they will only experience a loss in time and energy. Whereas in gambling, apart from an uncertain income, every gambler will definitely face the risk of losing their money.
The worst thing that the employees can get is fired from their job, making them can't receive the payment. But the gamblers can't always make money every month because the gambling itself is not predicted when we can win and lose. But the loss of money in gambling will always be wide open, and only people who can control themselves and manage their money that will survive, and perhaps, they will have a chance to make money. Only a few people use gambling as a profession, and they really know how to treat gambling as a profession.