Gambling is unpredictable, and relying on it as an alternative source of income is unwise. In fact, the main source of income will suffer because money will always be deducted from it to fund gambling, and the person's main source of income will soon begin to decline. Gambling appears to be a simple way to make money, but it is extremely destructive.
I recall a worker who retired with nothing to show for it, despite the fact that he had previously held a large and lucrative position, and it was later revealed that he was a gambler, and an addicted one at that. He sold his car to cover debts incurred as a result of gambling. Gambling should not be used as an alternative source of income.