If you make speed easy to get: every eg junior doctor and every lorry driver will end up having to take it in order to compete.
And dope: the prozzers will all be forced to take it, and factory workers will all take it.
And they should be allowed to do so if they wish. Or choose to preserve their health instead.
It is like banning woodcutting because it is a dangerous job.
If this gets to be the case, you will likely see laws being made that insure fair working conditions where workers don't need to do drugs just to keep their job.
They will probably not be allowed to hire people that use speed in these industries.