My experience in unmotorized outdoor athletics is that around half the folks there are hippiesque pot users and the others are pure athletes. That has been true in skiing, paddling, climbing, and even hiking.
Mountain biking has been different. My early rides (I'm 70 now) were in a haze of skunky smoke and everyone there was offering a toke or two. Red veined eyes, ravenous bikers, and perhaps a little apple dapple or boones farm.
Now, mtb has matured and is turning into one of the worlds great participation sports and I suspect that the 50/50 or so is true in mtb today.
To each his own, if he can.