First of all, I don't think quality of life necessarily translates to years spent living, or at least that's very hard to quantify.
For the Quality of Life vs. Long Hours:
Firs of all, it's also a weak comparison. You can work at a job 8 hours a day and hate it while the guy next to you does it for 12 hours a day and loves it. You might end up ruining your quality of life and he won't be. So you can't quantify your quality of life with time spent at work.
But even considering that there is probably a strong correlation; fortunately there is also a very natural balancing mechanism. If work long hours is really ruining your life then that's a direct incentive for you to not do it. You have a constant pressure to not overwork yourself because you it psychologically make you feel horrible and no one wants to feel horrible. So things sorta tend to balance themselves out. Even if you look at environments/careers were people really push themselves due to competitiveness in the long term I don't think they end up having shorter or worse lives.
Sure there are masochists that work 12 hours a day, hate it, but do it for the promotion; but even for them I think in their minds they don't have a horrible life. The prospect of the promotion prolly keeps them happy and keeps them going.
Now compare that with taking a pill or zapping your brain: If you take a pill and you get dementia 40 years later then you're trading in current gains for future pains. You're not getting constant negative feedback to hold you back. So to keep up with your peers you and all the people around you will be popping every pill possible because otherwise you drop out of the race.
Now since there are no brakes to the process and everyone is trashing their bodies to make it to the top your society eventually ends up with a group of super smart pill-poppers and brain zappers and they become all the CEO and PhDs but live to only 40 before their brains are fried and then you've got the rest that live to 90 and clean toilets.