Let's assume you're all intelligent enough to know the risks. Personally, I drink, but I've never smoked or taken recreational drugs. Ever.
Smokers know they're paying a massive corporation to kill them in a hideous, painful way. Hell, if I wanted to pay to kill myself, I'd buy some rat poison or hire a hitman.
In the UK, the criminal figures surrounding drugs refer more to possession than use. If you have a sly joint inside your own home, the police won't kick your door down 3 seconds later. If they catch you dealing it, or if it's on your person or if they find it in your home etc., that's a crime. That's a risk of drug use (getting caught), but so is dying in a pool of your own vomit, or dying of everything-failure induced by taking ecstacy. Why bother risking drug dealers? If they were selling used cars, would you buy one from them? No.
Drinking is the most acceptable out of the three. Homebrewing spirits is illegal here, but it's actually do to with taxation rather than the obvious health risks from dodgy homemade Firewater. It's nice to have a few drinks in the pub on a Friday night, to wind down after a tough week doing whatever.
I don't mind people who disagree with drink/smoking/drugs, but I do mind those who think they're God's Gift just because they choose not to get involved themselves. In any case, I've been told by numerous people that Alcohol + Smoking weed = Extremely unwell for a few hours.