I agree Ukraine never had a chance against the far superior Russian military. The reason the US and NATO did not officially send ground troops, although many of their people are on the ground, is that it would trigger full war between NATO and Russia which would go thermonuclear. If that ever happened, Russia's larger and more advanced nuclear arsenal (ballistic missiles) would give it an advantage. Their large land mass, twice that of the US, would give them a better survival chance after the fallout.