Governments exceed their proper powers when they force persons to do things for their own good, or when they forbid persons from doing what might harm them. The relationship of government to citizen is not one or parent to young child. Governments exceed their proper powers when they forbid persons from gambling, because how people spend their own money is their own business.
That said, I do not believe anyone should choose to gamble, because gambling is stupid. With gambling, there are always more losers than winners. Every dollar won is at least a dollar lost. Gambling does not generate wealth, but only moves it from the many to the few. It is harmful to individuals, families, and societies and contributes to addictions and crimes. Gambling casinos are not victorylands but loserlands. Gambling casinos attract organized crime. People should not waste their money gambling, because there are many better ways to spend or invest money. For most people, gambling is a source of impoverishment than of enrichment.