US benefits form NATO providing a forward defense. Is that defense needed now that NATO is on the verge of final containment? The US protected sea lanes for alliances. EU has the resources to match Russia which is imploding. This presents an opportunity to safely withdraw from NATO after a Ukrainian victory.
This is an apex perspective. Putin’s conduct caused Sweden and Finland to join NATO. Soviet subjugation caused Eastern Europe to join NATO. They understand evil. Who cares what evil wants? Ask what Ukraine wants. It’s their sovereignty, of the rule based order, that US Russia and UK agreed. The outcome is inevitable, a Russian defeat. The Ukrainians had a taste of freedom and they are not going back to subjugation.