For an 18 year old with no way of paying for college, loans are hard to come by, they can get paid to go to college and most likely be a better student and more successful due to the "real world" wake up call you get by serving in an "at war" Army.
Not to mention, when you compare casualty rates it's nothing like wars of the past. During the Ardennes offensive in WWII the US Army suffered 50k dead in roughly a two month period. A soldier today can get the same GI Bill without the same risk of death.