I believe that last half of a century of relative peace in the West is the direct result of the "bravest" (whatever that label means here) in two world wars. So that less brave men (and women) could build in peace. Unfortunately the population of brave men mostly recovered and we are ready for the next great war in Europe that will devastate everything.
It's different when you're randomly drafting conscripts from the overall population though, vs having "brave" genes self-select into mortal combat before they can reproduce.
There is no pure randomness in draft. People who know better are more likely to dodge it than "brave" people. Especially if the you draft significant percentage of men. You'll find out that nearly all that managed to avoid the draft are not "brave".
