Wrong question.
What national interest in Ukraine compels the USA to sacrifice, when all of Europe together can handle the backyard problem it has.
The answer is that we have nothing to gain and too much to lose.
You telling me that I’m asking the wrong question just shows you have no answer to my original question of why it is in our interest to have Russia take Ukraine. Giving a few dollars to help an ally repel an attack by an openly hostile country makes sense to me. You may see it differently, but until I hear an actual answer from someone, I will continue to be skeptical of anyone’s motives who says no more aid to Ukraine.