It was Obama who started pushing for the 2% policy and got NATO countries to agree to ramp spending up to that before 2024[1].
Before that there's been decades of the US trying to push Europe to take defense spending more seriously.
Trump's had more juvenile rhetoric on the issue, but he fundamentally wasn't saying anything to NATO or enacting any policies that Obama pursuing before him.
1. https://www.nytimes.com/2014/03/27/world/europe/europe-begin...
Biden will likely mark a return to the old haggling, but in 4 years' time the US might get another strongman and we'd be at risk again. Democracy will always need an arsenal, and it's not a given anymore that the US really want to be that arsenal.
You don't have to project power to distant places only directly via supercarriers and local military bases, various subversions can get you pretty far.
This laziness will probably bite us in the ass at some point. Trump was the first but won’t be the last US president pushing for disengagement from the Old World. You cannot build a superpower-sized army in a few months, and direct threats are only increasing (as well as Russia we now have Turkey, Lybia, Egypt, Algeria, Serbia - they could all go rogue at short notice and literally start firing shots at the continent).