Because if you had actually been in anything remotely resembling a combat outfit, you'd know better than to go around pontificating with these "facts" of yours.
And considering that there are cases of world-class athletes who smoke, I have a hard time imagining you have a clue at all.
You never saw a smoker lung, huh? Small, black, snail-formed gooish something. Don't tell me smoking doesn't affect a soldiers's endurance, because it does. Of course, it always depends how much you smoke, but say you get 12 cigarettes a day, after 10-15 years, you're going to have a desk job, or as Pidesco said, you're going to throw darts.
See you on the battlefield running out of air, you heavy smokers!