Sports does have risks like you said, Karl. One out of a infinity of things that has risks involved, but one difference is that sporsts doesnt give you braindamages etc by just performing them. Accidents can happen, and thats not a whole lot you can do anything about other than maybe being a bit careful, like checking one extra time on the wire that you will use when you bungeejump or whatever, and not doing stuff you know you cant really handle yet. Also activity makes your body stronger and when you succeed with something you get happy about the brain will reward itself in a healthy way.
Drugs however doesnt do anything good to you. You damage the brain everytime you do drugs. The brain also "rewards" itself way too much wich is the reason to why you get all high and also the reason, in a bit longer persective, addiction to whatever youre using and when youre there youre in the bad spiral wich we all know where it ends if you dont stop with it in time. You wont die from just performing a sport itself but might die by a accident wich is a risk that is very minimal. However, drugs will kill you sooner or later by just "performing" them alone and thats a huge difference.
So yeah, you cant compare sporsts to drugs. As I see it it was just a typicall excuse from someone who thinks its cool to try.