No, he doesn't have to give up from gambling. He can still use gambling to fills his free time but he must know how to control himself. Gambling can makes someone forget about controlling himself easily so it is better if he doesn't playing gambling too often.
The government should cares about their citizens and if closed the gambling sites or offline casinos is a good decision, they can do that. All of that is because they don't want to see their citizens becomes addicted to gambling. They can get the tax from the other business in their country.
Don't you find a contradiction in your words? Is it really profitable for the government to take care that its citizens do not become addicted to gambling? No, it is not so. If a person stops playing, then taxes will not be collected from him, and the casinos themselves will not receive income and the state will not receive anything for the treasury. So think about this fact. Yes, I understand that it looks very cynical, but this is the current reality and nothing can be done about it.