I don't think that's the main reason we have regulation. Preventing individuals from externalizing costs to others, against their will, is more common and much more justifiable.

The some obvious examples are environmental and food safety. Another is financial regulations to prevent "too big to fail" institutions from taking wild risks that result in bailouts with taxpayer funds.

Food safety regulation has nothing to do with unpriced externality and everything to do with people not knowing what's good for them.

Food safety regulation isn't about making me to eat my vegetables. It's about making sure my vegetables aren't contaminated in ways that I can't reasonably detect.

A producer who skimps on food safety can save costs, and the externality is people getting sick, through no fault of their own.

That is not what "unpriced externality" means.

And if your vegetables being "contaminated in ways that you can't reasonably detect" isn't a case of you not knowing what is good for you, I don't know what is.

They don't. But they ought to have the right to decide what's good for them, even if they're wrong.

But it's government's job to make sure its citizens don't get conned. People have the right to decide to join a suicide cult, but also the government needs to stop the cult because otherwise all these innocent yet naive people will die.

Why is it the government's job to ensure people don't get conned?

because thats we as a society agreed was the governments job.

You are arguing what is. I'm arguing what ought be. I believe it is a violation of fundamental human rights to prevent people from doing with their own property what they like, provided that so doing does not impinge upon the rights of others. My right to be taken in by any scam I choose ought to be absolute. If, ex-post, I can show that I was conned, I ought to receive compensation for that, and maybe the perpetrators ought to go to jail. But the government shouldn't stop me from doing it.

That's your opinion. I'm not saying there's anything wrong about it, but it's just that a modern capitalist government's priority is to make sure its society stays stable (unless you think its priority should be to seek chaos) because that's what governments were built to do--to provide stability.

What you're not taking into account is macroeconomics. When you let anyone do whatever they want, it is very likely that the rich will get richer (because they are more informed) and the poor will get poorer. And with that comes corruption. That's why the government steps in to break off organizations that become too large and make sure things like antitrust don't happen.

If you think the society is unjust, first try to learn WHY things work that way, that way you may either come up with a solution that can solve it, or go build your own nation, or at the least understand what's going on.

thats not at all why we have regulation?!?

we have regulation to prevent people from being misled.