Governments should not interfere with the private decisions of adults. If people want to gamble, let them. If you do not like gambling, then do not gamble. But do not use the government to force your "moral/ethical" preferences on everyone else.

That works in a world where everyone has equal knowledge and ability all of the time. Unfortunately, when that is not the case, sometimes humans have been known to take advantage of others. Due to this, every society on earth has created rules against various types of these situations.

Yeah great idea! Let’s also just legalise recreational fentanyl while we’re at it

Should there be taxes on alcohol and cigarettes? Should there be warnings on them? What about on heroin?

Next time there is a fire at your house I will say "he's an adult who should have been careful playing with dangerous things like fire, we shouldnt waste society's money and resources on saving his house"

yeah, lets make a government to enforce that.

There are entirely practical reasons that "private decisions of adults" can worsen society as a whole. We need laws and we can debate about nudging that line back and forth, the answers aren't easy. But acting like there shouldn't be a line is nonsensical.