A number of great composers were fond of the bottle, but can you hear it?
spectator.co.uk
spectator.co.uk
When they can't surround themselves with other original thinkers, or develop a saintly patience for the plugged-in, the only option left is substance abuse.
Judging from "Behind the Music," substance abuse is the path of least resistance.
There's also the conundrum of writers using amphetamine, like Hunter S. Thompson did. Tho he (ab)used more than just that.
Whether one uses a particular drug is clearly not the only thing that determines "greatness". But some drugs could help increase one's creativity, or to "loosen up", shed inhibitions, see the world in a different light, or appreciate things you otherwise wouldn't. There's often a cost to this, sometimes it is a great cost, but it's a mistake to believe drugs are an unmitigated evil without any benefits.
The real problem is that most people aren't taking drugs for constructive reasons, like to enhance their creativity, but either for frivolous or self-destructive reasons. Of course, even constructive uses can get out of hand. That's where education, discipline, and support come in. Unfortunately, modern societies do a pretty poor job of helping with any of these things, and focus primarily on stigmatizing and criminalizing drugs and drug users.
They can also act as temporary solutions to permanent problems - many people self-medicate with alcohol or other drugs.