Your inviting some chance of failure every time you decide to play hopscotch on a piece of architecture, and sometimes that failure involves losing your richard to a metal fence.
Part of parkour is being sensible and knowing when something is too much for you, you are inviting a chance of choking every time you eat a hotdog and you could easily get hit by a car when you cross the road.
It's still one of those things which inherently annoy me because of how overrated it is. Like zombies, or fedoras.
I thought everyone hated fedoras :/ and it is unfair to judge everyone that does it as "trying to be cool badass hipsters"
There is as much danger as most other sports.