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.