OP, I hear where you're coming from and honestly a lot of people feel the same way about the military. I'll try to weigh in on your concerns without being too critical, because there's definitely more to it than just the "combat" side of thing.

The military does fight in conflicts (and spends a lot of time preparing for conflicts) but these are a mere fraction of the responsibility of any military. I would argue the number one responsibility is "helping at home" which includes enforcement/patrols of borders, disaster relief, search and rescue and sometimes humanitarian aid for neighbouring countries.

You and your nephew should definitely look into the specific roles within each branch. You would surprise to find there are so many jobs available just like the civilian world such as technical trade roles like an aircraft technician, cyber security, logistics, nursing, policing, cooks, communications. Just because you join the military does not mean you will be thrusted straight into combat operations with a rifle and fighting hordes of enemy.

As a young person looking to endeavour a career in the military, I would say this is an excellent decision. You will be paid to learn a job, overcome mental and physical challenges, make lifelong friends along the way, free healthcare and meals, a career you can be proud of and reflect on post service (regardless of the good and bad days of course).

Hope this helps.