Anyone who wants to play Russian Roulette is suicidal. There is no other explanation. No amount of weed or laughing gas is going to make someone suicidal. People who turn to drugs before killing themselves are doing so to self-medicate and to kill the pain. It is not the drugs that drove them to do it, but the other way around. People are always looking for a boogieman to avoid confronting our own true nature and our own personal demons. Some people do drugs for the thrill, but they can usually stay functional and know when to say when. Many also do so as a coping mechanism, and they tend to be the ones who go way overboard. They may lower one's inhibitions and can certainly make a bad situation worse, but they do not fundamentally change who you are.