I don't quite understand where you're coming from here... Do you mean, is drug abuse responsible for those bad things? If so, NO! If someone sexually abuses someone else, then they were predisposed to doing so anyhow. If someone blows their head off, well, they likely were retarded/depressed to begin with. Drugs might amplify something, but I wouldn't blame drugs on it. Blaming drugs is the biggest cop out of all. Using drugs is a choice. We must all be responsible for our choices, and the actions we take. If you rape/sexually abuse a child, that is just a way to minimize it for yourself and those around you.
People do fucked up shit sober. Hell, my exhusband raped a 6 year old child sober. I'll give him this, he did grow up in a family that is nothing but sexual abusers/rapists who had sexually abused him from an early age, in a very chaotic household. That's not to give him an out, but it does explain it a bit, but even after all his rehabilitation and remorse, he continued to sexually abuse just like his family, and manipulate, both on and off drugs. he never had any genuine remorse, even going so far as to get a tattoo to commemorate the injustice of the law... because of the time he got for what he did (which was a drop in the bucket to what he should have), and because this little girl had been being rapped and sexually abused by others and they didn't get caught, and he felt some things were lies in the reports (I don't believe that, I think he said that so it didn't seem so bad to everyone else).
I am a firm believer that people can change, even someone as fucked up as him (and no, not even if he did would I ever want to even be in his presence much less back in a relationship), but from his actions I've learned about, no, he has not, and most people don't. I don't know that he has raped or sexually abused anyone recently since me (wouldn't surprise me though), but when you continue the same sort of patterns, like jumping into relationships, and rushing them so quick like he tried so hard with me and before me, it's a really big red flag that there is no real change, just the sign that he found another victim to use and abuse.
People need to look at themselves, see the ugly truth, that it is them beneath the surface that is what wrecks the ill in their lives, not the drugs, not others on the outside. It took me a long time to see this for myself. Drug use tends to be involved because it can be a very selfish and self destructive choice, but it's not the reason for it, just a symptom in some cases. Sure, you have the times where people do stupid things while on drugs and drugs automatically get blamed- example, a acquaintance of mine, who was very, very good friend with my dealer, ended up blowing his head off with a gun. Sure, the family and even some of his friends wanted to blame drugs, but on more than one occasion he had played around and joked around with the gun, holding it to his head. People had warned him. He fucking should have known better. Drugs wasn't the reason this happened, the reason he ended up accidentally killing himself in front of his friend was because he was an idiot who was showing off how much of a badass he was. He would have done this completely sober, it's just the kind of person, of idiot he was. He was a really nice guy, I feel bad for how it all happened, as I really did like him, despite this stupid flaw of his for doing stupid, dangerous, needlessly wreckless shit just to prove how "cool" he was. Now, saying all that, it'd be nice to be able to excuse his stupidity with drugs/the gun/or some other thing, but you can't. Maybe he wouldn't have died that day, that way, as he did, but I bet he would have done it some other way, some other day, being an idiot, showing off, or at least have seriously maimed himself or someone else doing something similar in a vying for attention in some deep seeded desire for love, acceptance, and to be thought cool/tough/well of by his peers. Funny thing is, he was already, without his acting out for attention, thought well of by everyone, including me, and these stupid acts really just did the opposite in a way. I wish things had been different, I wish he hadn't have accidentally killed himself (at least though, it was him and not someone else), but he did, and blaming drugs doesn't make it better, in fact, it makes it worse, because now you have people looking away from the real issue of what caused it (obviously, he had some kind of inferiority complex/feelings of not being accepted/urge to need to prove himself when there was nothing he needed to prove), rather than trying to help people with their problems inside themselves that go much deeper than drug use.
... and that's my two cents.