military service in US is largely coercive in nature. The US intentionally keeps people in poverty to make military service an attractive option. And the ruling class is quite open about it. https://truthout.org/articles/gop-student-loan-forgiveness-hurts-ability-to-lure-poor-people-into-military/
You also have to remember that people living in US are subject to the propaganda and brainwashing of the regime.
Young impressionable people are told that they can escape their horrific conditions by serving their country. they don't simply don't know any better.