It depends on one's income. The more you can afford, the more you can spend on gambling. But we should not spend more than 3-5% of our income on gambling.
Even if someone have a big income, he can not use too big money to placing his bet. He must adjust his income and know how much money he will use to playing gambling. The important thing is you only need to use the money you can afford to lose to playing gambling. You will not playing gambling using too much money because you know the risk behind that. You can prepare some money you will use to playing gambling and will stick to that while you will not add more money to playing gambling.