Since I was 4, all I ever wanted was to be a nurse. I was very bright, but teachers always described me as an "underacheiver". I think I was actually ADD. Didn't like to study. Turned out I was extremely near-sighted, which was discovered just before 9th grade. (I had gotten D's most of 7th and 8th grade.) I started getting better grades cuz I could see what was going on, but by then, the no-study bit was a habit. I could get c's and b's in HS (even a Catholic school) w/o studying, why study?
Got accepted @ college (Univ of Hawaii), but not into the nursing program. So, I started taking the same courses as the nursing students-anatomy, chem, micro, but I couldn't get away w/as much stuff in college as HS. It also didn't help that after 3 yrs of all girls, there were men around, and that became VERY distracting. UH had a policy that you could basically cut as much as you wanted as long as you showed up for midterms and finals. I flunked out TWICE!!!!!!
My parents were paying, and my dad had told me: I have this much $$ to send you to school, when it's gone, you're on your own!
I guess what I'm saying to you is it sounds to me like he's fooling around, all right. IMO, you may need to deliver an ultimatum: turn it around, or get a job and forget about school, at least for NOW. Not forever!
After the 1st flunk out, I decided I need a Catholic hospital school on the East Coast where I wouldn't be tempted to go to the beach instead of class, and there would be plenty of external discipline! Cutting class would soooo not be an option. And that is exactly what I did. Altho there were a few near misses when things got scary and I almost didn't make it (depression, homesickness [family moved to west coast]), but ultimaltely, they gave me my black stripe and my diploma and I passed the Boards 1st time, got a job @ a hospital I stayed @ for 34 years. STABILITY!!
I made a pact w/another student to stick it out, and some one told me something that turned into a motto: "Sacrifice immediate pleasures for ultimate goals."
Good luck--let go as much as possible. He's not throwing his life away for good. There are plenty of threads here w/people saying "Is it too late @ 30, 40, 50?