Does this mean cigarettes are a good thing? Why do they exist in society if they so clearly harm people?

There's a big industry around smoking that has managed to perpetuate itself in society despite the fact that it causes harm. This doesn't mean there's a good reason reason for it to exist; the reality of the situation is that you can entrench yourself in society and become very difficult to remove if you have enough power to do so. It might be that in 100 or 200 years the cigarette industry is finally gone.

Pretty much the same applies to Casinos. Yes, people play at them, and a lot of people that go to Casinos have a gambling addiction. For some, perhaps most, casinos provide a degree of entertainment that is not really a problem but ultimately Casinos are set up as a business that relies on people losing more money than they win. There's things like lotteries which seek to channel gambling addiction into social good.

And even in this scenario; Casinos are highly regulated. Which crypto ponzis are not. The existence of crypto gambling is simply a failure of regulation which is slow to adapt to new technologies. Yeah, crypto bros are in luck that there's an administration that goes as far as to encourage people to fall for these scams. It doesn't mean it's something that's going to last.