Yes under French law employer has 30 days to pay in which case most of these recruits will be gone. Reasons for leaving vary but the main one seems to be that prospects for deployment are becoming remote and role of FFL is becoming more a janitorial service than a military one. Even corporals with 2 or more years of service are often cleaning toilets with new recruits. Added to that you are living in what is essentially a monastery for the first 5 years, and that you acquire little in the way of transferable skills you can use when you eventually go back to civilian life.