Russians are lining up to go to war under the promise of money, around 30k a month last time I checked. Americans not so much, in particular not against Europeans. It's different in my view.
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.