Supporting Ukraine’s defense against invasion has had better ROI than most domestic defense spending. For a pittance we’ve let a major adversary weaken itself considerably. We should do more.
Weakened only in the personnel sense. In terms of industrialization for war and acquisition of modern warfare tactics, we have made them considerably stronger.
Nope. Russians have improved in some areas (experience), but they lost a tremendous amount of war materiel, and the economy suffered significant damage.