"If all of your friends were jumping off a bridge, would you?"
I dunno, if all my friends were jumping off a bridge, there's probably a logical reason. Are we being chased by someone with a gun, and it's jump or be shot? Are we jumping to some water below to try and survive a big forest fire surrounding us on all sides? If everyone is doing something so drastic, there's gotta be a reason, not just "lul lets all kill ourselves for funzies hehe"
The jumping off a bridge thing is such a weird hypothetical to me. It's so extremely unrealistic. I've seen it in media all the time growing up, and having been homeschooled and generally isolated from the outside world, i thought it was just a thing on tv. But growing up and talking to people and finding out grown ass adults have actually said this shit to their kids is fucking wild to me. And it's said because a kid wants to dress a certain way or for some other benign trend.
The jumping off a bridge thing is ultimately just another "because I said so" but with additional faulty logic sprinkled in.
Parents saying no to benign shit also weakens the power of that no when that same parent tries to ban their kid from doing something actually dangerous, because from the kid's perspective, if you always give such a strict no to the most benign shit, how are they supposed to know when you're trying to ban them from doing something actually dangerous? Of course one way to help this is actually explaining why you don't want them doing certain things. "Because I said so" is never going to help the kid understand what's dangerous vs what you just personally don't like.
Yes, even if the problem is finances. Even as a pretty young kid, i understood when told that we barely have enough money to buy this regular food right now and can't get candy. I might have still been disappointed, but having the why always hurt less than "because i said so" because that just feels more personal. "Because I said so" can feel like you're being punished in a case like this if you aren't told that the actual reason you're not getting candy isn't your fault.
Like it helped that even as young as like 4-6 years old I was shown how much food costs, which is why I still remember that in the beginning of the 2000s you could still get a shopping cart full of groceries for less than $100 if you shopped somewhere cheap. Food is several times more expensive than it was when i was very little.