The military is unfortunately chock full of functional alcoholics. As long as they don't get caught drunk on the job, seen partying too much, DIU, or admit anything to their doctor, they keep getting renewed their clearance.
Interestingly enough, if there's even the smallest suspicious that you smoke weed, they'll put you through the wringer. I've seen more people lose their clearance for pissing hot, than those with six figure debts or drinking 5 days a week.