The person who invented the trampoline probably had some very useful, necessary need for it.  They probably never intended it to be the machine of mass destruction that it has become today.

But if they did, then they are somewhere laughing right now.

Most of the trampoline accidents in the video are the result of sheer stupidity.  The temptation to see how high, far or how many flips you can do in a jump is just to great for some people.

Trampolines Are Dangerous