For starters, someone who has actually been in the military.
Your examples of people who are destitute, legally obliged, or have no prospects other than the military are a far cry from an 18-year-old who works two part-time jobs to make their $450/month car payments. The types of people you described don't have $450/month to make car payments, let alone have a car.
The only thing you said that I agree with is that ultimately, it is his choice. There's nothing wrong with a shot of reality from those with military experience and my experience has shown me that those who join because they really want to have far more enjoyable and productive enlistments than those who are worried about making their car payments. The guy has admitted that he's no rocket scientist - what type of MOS is he going to qualify for? Kind of hard to enjoy your $450/month car when you're on watch from 0000-0400 after an 8 hour patrol in Fallujah...
BTW, someone with an avatar of a soldier sporting oil company patches giving advice about the military is FUBAR.