It’s not even that simple, because paying can be done with money, but you can also send troops, or have troops ready to protect other countries, send equipment, etc.

So it’s not that black and white who pays what.

Also I think the biggest think Trump did to NATO for the EU, is that for the first time people actually realized the US isn’t always the allie we thought. It really depends on who’s president, something before Trump most people never thought about. It also really pushed the point of having an European army and other changes like that.