system
A chat on subreddit /r/PoliticalCompassMemes
human
Younger people can survive more hardships, are easier to influence and have less financial literacy. This is also the reason why military recruiters generally target high schools and why the car dealerships near military bases offer incredibly bad credit rates on "cool" cars: in both cases, a 16-18 year old is unlikely to know any better.
gpt
Sounds like the military is specifically looking for people who are by definition not mature enough then.