The US is taking advantage of a golden strategic opportunity, because why wouldn't they, but it's Russia scoring the own goal here. If they wanted to stop destabilizing themselves they can always leave - the war ends literally the second they turn their tanks around and drive home. Nobody is going to follow them into Russia. They don't even have to do anything diplomatically. Just leave, no special agreements required, and the war is over.

A peace that grants Russia the Sudetenland as a consolation prize along with a guarantee that Ukraine is sovereign (but with a big asterisk in that they are also not sovereign in the sense that they are able to join an alliance of their choosing to protect themselves from aggressors) is just an invitation for Russia to consolidate the new territory and prepare the next push. And not being able to see that is for me much more shallow thinking.