I do think that people underestimate the dangers of prolonged stress.

My hypothesis is that stress is the real killed. This might be survivorship bias, but I often see people that are above average old, smoking. That's why I think that perhaps the reduction of stress that smoking provides, could be more beneficial than the negative side. We do know that nicotine does have a neuroprotective effect and smoking does include a specific way of breathing.

I'm not saying smoking is good or that anyone should smoke. But I do think it's worth investigating.

I personally try to avoid stress whenever possible, of course, within reason.