This line of reasoning goes to a dark place. You can't know what makes sense in someone else's life. A heroin addict self-medicating unbearable pain is, to me, a tragic figure deserving help. A morbidly obese person may be suffering from an undiagnosed underlying condition that makes diet and exercise impossible. A smoker may need the stress release.
Should we refuse to treat any injury sustained by the Wright brothers during their experimental flights? Surely that's highly dangerous highly voluntary stuff. Should we refuse to rescue hikers if they become lost or trapped? Should the coast guard never help recreational sailors? Should we have to submit to a proscribed diet exactly to prove we deserve medical care? Should we forgo treatment for tendonitis if it can be shown we ignored known warnings about typing too much?
To me, people are precious, and they lead messy, imperfect lives. They make bad decisions and good ones, and decisions I don't understand. They'll take risks I never would in pursuit of goals I don't see as valuable. Sometimes, when you really get to know someone, a decision that didn't make sense from a distance really starts to. And sometimes people are being self-destructive and there's no more to the story, and sometimes it's something they go through and come out the other side of.
My conviction is to love and help them no matter what.
Sometimes I can't, and that's a different thing, but deciding that someone doesn't deserve help is a level of judgement I don't want and can't justify. Maybe what they were doing really was worth it. I don't know. Even if it's not, it's essential to let people try.
I would find someone else trying to exert this degree of control over my life - requiring me to comply with their particular take on what risks were worth it - suffocating and unbearable. I am sure others feel the same way, about control in areas in which I wouldn't mind it because I happen to already be normal. So I am against it on principle. People need to be people, in all their messy glory. And we should help them if we can, regardless of how they got there. I think the only case in which I would act differently was if I thought letting someone suffer natural consequences was for their best - and I would have to be incredibly sure.
Leaving people to a fatal condition when we could help them is incomprehensible and inhumane to me, and represents a dangerous level of escalating disagreement into dehumanization.