Why the fuck is it any of their business what I do in my free time?
Its the same thing you do when you find a skunk roaming the house, you either get a broom and shoo it away, or restrict its freedom so at least it doesn't spray anything. What the fuck gives you the right to put the skunk in a box? The right of the others to remain un-sprayed by twitchy tailed skunk.
Of course, when you adjust for the number of users the rate drops to lower than the rate for alcohol (duh).
[0]: http://www.vox.com/2014/8/2/5960307/marijuana-legalization-h...
The answer is: that's absurd. Every single thing humans do can result in injury. (Even sitting in a chair injures you!) Cycling probably sends more people to the emergency room than smoking pot does, in fact.
(I don't use marijuana BTW, but I do support its legalization. Sounds like a legitimate recreational activity. I personally prefer coffee.)