Making them military slaves would not be much of an improvement. I spent 4 years in the Navy, fortunately in peacetime. Now we have perpetual war so you're risking your life if you join the military. 

Those you see downtown are only a small percentage of the local homeless, who come in all ages, including old. I'm told by someone who knows these kids downtown that many of them are not homeless. Of those who are, most did not choose to be. Downtown has always been a gathering place for the young. You do not have the right to tell anyone how to live, nor the knowledge to have an informed opinion on homelessness.