I bet if the Romans had a fleet of C5's, satellite communications, and AR15's, they probably would not have fallen.
I have a feeling they just stretched themselves too thin. An interesting read is the autobiography of Julius Cesar. It opened my non-military eyes to the logistical problem of moving a military during the days of horses. Imagine the supply lines. Imagine soldiers showing up and stripping the land and livestock bare. Eventually it has to give out, because you just can't move enough goods by horse.
I will agree, we're in a pickle though. Too many people want a handout, too many people just want easy street. Don't want to work. Many Americans lack the motivation to actually accomplish something in their lives.
Social Security will be gone by the time I think about retiring, I have no doubt. And I wouldn't be surprised when they want to absorb 401k accounts in to Social Security. That'll be a domino that really pushes a lot of buttons. At that moment, I'll withdraw my 401k and spend it on ammunition and canned goods.