Motorcycling does not cause immediate harm to society or to the individual, and is a regulated activity anyway.
Alcohol and tobacco are regulated too. Perhaps less than it should, in no small part for cultural reasons. I say this as someone that enjoys the occasional whiskey and smoking a pipe.
I am unaware of evidence of gaming causing harm to society. Maybe it exists. I can't comment on it.
Many things that people enjoy are banned because it causes harm to other individuals or to society as a whole.
Not a difficult concept to understand.