I was a fire bug and built explosives when I was a kid...
Used to go to the public library and research certain devices and build interesting things. Liked the cherry bombs, I used a custom made "wrist rocket" and could launch those things a city block... into an intersection that three main streets crossed. Used walkie-talkies to change the angle of the cherry bomb to get it on target (the intersection)
The 5th of July I would wake up early, get some of my brothers and we go out picking up dud firecrackers etc (fireworks were illegal in Chicago) Get a grocery bag of those and remove all the gunpowder. Manufactured a few pipe bombs back in the day... blew up some rather large trees and things.
Then we built napalm type devices since what good was an explosion without fire? Had a lot of fun, didn't burn the house down and the people in my area thought me and my brothers were a little crazy. I never got into rocket motors (my older brothers did) They did the sky rocket/M80 bundle trick, I used bottle rockets setting off M80's on old toy car bodies.
The reason none of my friends and family never were injured in any of our experiments is we understood what danger was. Playgrounds were paved, monkey bars and metal slides that would burn your butt in the summer and ice ball fights in the winter. Grab a car bumper and go "skeetching" at 30MPH on the snow taught balance and how to evaluate surfaces. Put a rope though the front of a sled and go screaming down hills standing up... crashed all the time but it was fun. The balancing act was also good practice for skateboards, roller skates and attempts at unicycles.
Bicycles dangerous?
Those things were transportation and still are. Sure custom made "choppers", BMX insanity and racing were common but the skills learned made it a very safe practice. The BMX days made motorcross motorcycles a natural extension so we stayed alive since we understood the dynamics.
When my teenage sons were younger, I made sure to expose them to various dangers of life so they would understand that hair rising on the back of the neck survival feeling. They both ride skateboards, roller blades and one of them almost has mountain unicycling figured out. They know how to correctly launch and use fireworks without blowing body parts off, starting the city on fire or getting arrested.
Over protecting kids just makes them sit around the house, play video games, watch TV, get spoiled, fat and ignorant of the world around them. I've run into many children that don't know how to ride a bicycle, climb trees and other various childhood skills. Pretty sad, most of the fun I had as a kid somehow involved experiences that I don't partake of in my adult years. Still ride bikes and play some games with my sons but I think I lost the window of opportunity to learn unicycling.
As adults we spend too much time inside, let the children go outside and enjoy the sunshine.