Software developement is in high demand in France too. (I arrived in the job market there a year ago and easily got a job)

I think it depends on your field/position. From my experience, anything else than management will get you a rather bad income. Most of "software engineers" in France are basically considered as making a job at technician/operator level. Some of these jobs are actually getting exported to India or Spain.

Well, it's still white collar work and if you have an engineer's diploma in software, you'll have higher salaries than a people with an equivalent degree (engineer's diploma) in other industries (construction, car construction). But you need that diploma, without it, the GP will have a very hard time finding any kind of position. Other degrees might give access to the job market, so, in his case, he should try to find a short formation giving him a degree so he can work. Currently some consulting companies (les sociétés de services) are hiring like crazy, so with a degree and some work sample, you might get a foot in the door.

I mean, $40,000 of student debt sounds like a great way to motivate someone to find work, but I don't think it's an ideal way to solve his problems.

$40k in debts to earn $80k+ per year for the rest of your life?

Sounds like a good trade-off to me...

Well stated like that it sounds like a good deal, but that statement makes a list of assumptions as long as my arm that quite simply are not guaranteed.

Well in this context we're talking about software dev so. College graduates still makes a lot more over their lifetimes, debt or not, than high school grads.

For starters, OP says that he has health issues. That makes it much more difficult to hold a full-time job. If he can only work part time, he would be stuck earning far below the full-time market rate. As total annual revenue decreases, the time required to pay off that debt, along with the total amount of interest paid servicing it, goes up exponentially. Going to university isn't always a guaranteed win.

I didn't say it was a guaranteed win

I have the french baccalaureat. To be honest, I doubt that I can really come to the US that easily, or I really don't have the money to do so.