With all due respect, that's missing the point. If you believe that NATO is a good thing and successfully deters aggression against its member states, Trump's near-abrogation of America's treaty commitments objectively did far, far more damage to that deterrence than Germany underfunding its army. Ergo, Trump's nonsense about "paying" and your defense thereof seems terribly insincere. Either you don't believe in NATO's mission, or you are confused about how it works.
I mean... what exactly are you arguing here?