The peers I knew who joined were middling students who were struggling in community college while working shitty service jobs and thought the GI Bill was a better option. Two joined the Navy, hated it, but used the benefits to go to college.

An ex-gf's family had some wealth but was dysfunctional, so her dumbass older brother enlisted in the Marines (classic crayon eater) for status. Her wealthier, smarter, and more heartless step brother got recruited into navy intelligence.

I worked at a high school in a low income, majority minority area and we sent lots of kids to the Marines (for some reason, that was the only branch that ever came to our school. Edit, sorry, now that I think about it, many Filipino students joined the navy). The ones who joined were usually good students who didn't have any family support to attend college, so they saw the military as their only pathway out. Two visited me after their time in the service: one hated it and the other became a recruiter.