Earlier quoted context omitted.
Because the USA needs NATO and other shit to have soft power and keep its hegemony. Shit like what you said truly makes me wonder about the state of education in the USA when you don't understand a basic geopolitical principle your country has enacted for 80+ years, with massive benefits.
Europe needs the US more than the US needs Europe as far as NATO is concerned, the defence spending disparities speak for themselves. I sincerely question the logic behind our servicemen putting their lives on the line for someone resenting America this bad.
As far as the USA hegemony is concerned, NATO is an instrumental piece of soft and hard power.
You are parroting Trump's arguments about defence spending as if the US spending is only concerning NATO, the US spend a lot in defence because it's been your bread and butter to maintain a global reach as a superpower, the moment you lose this you'll see America's influence diminish, if that's what you wish please go ahead and pull out but so far it's been very beneficial to you in the USA to be the de facto global enforcer during Pax Americana.
> I sincerely question the logic behind our servicemen putting their lives on the line for someone resenting America this bad.
Geopolitics are not based on feelings, it's based on advantages and trade-offs, your feelings don't matter for this.
Coming from a person that once said in a comment "love is a mental illness" you seem to be quite the non-rational actor, with knee-jerk reactions when your feelings are hurt. Try to comprehend that the life as you know as an American is dependent on keeping your dollar as the most powerful currency, which demands being backed by the most powerful military, with the most trading routes possible, and with trade as stable as possible around the globe.
NATO is just a piece of the puzzle, it's not about what the others allies feel about you.
You are also forgetting 4 years of Trump with a possible re-election of this piece of shit, there are reasons for allies to be resenting America, it's becoming unstable and less trustworthy.