I’m a product of Army ROTC. I retired as a Lieutenant Colonel (Special Operations Planner).
Your son should look at all 4 services. Each is different.
Once he decides which service, he should very seriously consider staying in college and getting commissioned via ROTC.
Even if he decides to enlist, he can get his commission in various ways. Educational opportunities in all services are tremendous.
Remind him that any job has a downside. That’s just life.
Psst, there are 5 armed services. :)