You actually see the same thing in artists. Sure, the top geniuses are prone to hard-life and drug use, but there are plenty of phonies abusing drugs and living the "life style" without producing any work of value. My gf is a musician and every time I hangout with her friends I feel like I am the dirty unhealthy one. Nearly all the musos are vegeterian yoga freaks, even the rockers, while I the computer programmer chase cigarettes with spirits like a "rockstar" :-P
I wouldn't describe Erdős's amphetamine use as "hard life". He wasn't taking the pills for euphoria, and his body survived longer than most people's; amphetamines in the doses he was presumably taking don't seem to cause much extra wear and tear on the body.
Basically, he tried stopping taking amphetamines, and was okay, but couldn't do any math without them. He was dependent on them.