That's a very strange topic title. What do you really mean by it? What, especially, do you mean by "can't"? Do you mean not capable of doing anything stupid? Or do you mean in some way not allowed to do anything stupid?
I don't believe anyone is incapable of doing something stupid. "He who never made a mistake, never made a discovery." (Look
here for more quotes on mistakes.)
Not being allowed to indulge in stupidity is something else. If someone else is legally responsible for your actions rather than you, don't you owe it to them not to foul up? Like it or not, that's the case with most kids and parents.
It partly depends on what you mean by stupid as well. Is this stupidity accidental or deliberate?
And this "what's the point of living" is open to debate too. I've discussed this before with other people on CFC and there are several distinct views and they're all valid. I would say my point of living is growth, and to grow I expect to take risks and make mistakes. You can bury me when that process ends. Others are not interested in growth and prefer peace, and I would expect them to be less likely to do stupid things as a result.
Your example question is too simply answered and makes too many assumptions. Why assume the parent would be mad? And you'd have to find out whether she did it accidentally or deliberately, and if deliberately, why.
Some people can learn from the mistakes of others. Some can learn only from their own mistakes. Some just don't learn. Most people are a mixture.
Everyone can have fun, teenagers or not. Reverse the roles for a minute: what would the teenager think if their parent did that? There's no simple answer that covers all cases.
Most parents want the best for their children. Many of them have some idea of what best is, or more exactly what best isn't. A parent's problem is compounded when they have to take legal and financial responsibility for the deeds of their offspring. That's tough if their offspring have a streak of irresponsibility.
And yes I am speaking from experience. I have daughters aged 22, 24 and 28.