The aviation profession is one of the few which rightly shuns those who use illegal substances. Compulsory Drug Testing for all airline crews will surely be here before long, as it is in the armed forces of many nations.
The notion that aircrew regularly drink to excess is about 15 years out of date.
So wise up, druggies. You will probably be caught and then slung out on your ear.
Unless, that is, you manage to kill yourselves and your passengers first due to being under the influence of the brain-rotting toxins your stupid and illegal habit causes to be present in your bloodstream.