Americans don't need money to fight. I was paid $0 with the YPG and had to bankroll my own time. Lots of Americans there. I met a lot of them that didn't even really give a shit about the sides of the war, they just needed to fight something. We're a savage people.
Which historically has worked more for us, than against us.
And also, our whole military recruitment strategy here outside of drafts has been "the GI bill" – paid tuition in exchange for lining up to go to war.
I don't know that the gap in morals is as wide as you think.