So, I actually identify quite strongly with your son. He was essentially me back in high school. I got very average grades, primarily because I hated classwork, and would rather hang out with friends. After graduation, I got a job, and tried to start a band for about a year, couch surfing around Oregon while I tried to start a band/land gigs. Finally, on a whim, I ended up walking into a recruiter's office. This was quite possibly the best decision I have ever made. Assuming he gets a good score on the ASVAB, and a high GT score, which I am sure he will, he will be eligible for all sorts of jobs, many of which open a wealth of possible future career options. I have no formal education, and due to joining the Army, at 24 I have a net worth just over 100k (Granted, due to finding MMM three years ago,) no debt, a paid off car, multiple certifications, free health care, access to the best low cost retirement plan in the world, (TSP) and a pension after 20 years. I am fluent in Russian, as the Army paid me to learn that language in an immersive setting for a year and a half, and then proceeded to spend another six months or so training me as an Analyst. I then spent the next three and a half years working attached to a 3 letter agency, with other services and civilians. I am now pending orders for the White House, to work there for a bit. I have multiple job offers, and some are very tempting.
I am not cut out for college, I have no interest in having to take courses that I am not interested in (core prereq's, ect.) However, I am educated, I love leading people, teaching my soldiers what I know, and exploring the world. There are so many opportunities in the military that people don't know about, it isn't just a bunch of roughnecks running around breaking things.. (Though there is plenty of that too.)
There are jobs in IT, cyber, plumbing/electrical/hvac, linguistics, and a myriad of other fields that companies pluck people from after their first enlistment. Think of it as less of a service, and more of a paid gig (decently paid) that trains people into skilled and experienced professionals.
And, well, you know, blowing things up every now and again is also a perk. Much of the pay is also not taxable, once you get to a certain rank/come in married. With all my allowances/base pay/special duty pay, I make about $65k, just over half of which is taxable.
Could I likely get a better paying job? Sure, but I love what I do, and the military has provided me with so much free training, travel, and opportunity, I can't recommend it enough to young people, especially those that are unsure of what to do, with the caveat that they are particular about what field they go in.