Well, it is bound to happen when one is a near-peer conflict, while the other was just colonial policing, yet the US couldn't even win, despite multiple shock-n-awe campains followed with hearts-n-minds.
If anything, your argument makes it more embarassing for them.
Because last time I checked, war was about achieving political, economical and geographical objectives, is not about Kill/Death Ratio, because war in real life isn't a Call of Duty game.
Finns like to cope how they killed more soviets that finns got killed, but Karelia and Petsamo are still part of Russia; the US killed plenty of vietnamese, still South Vietnam hasn't been a thing for over 47 years; the US managed to wipe 20% of the population of North Korea, yet the US doesn't dare to touch them nowadays, and so on.
Not that I disagree with your point, but Russia can't ignore the losses either. The Russian population is on a historical decline, with no immediate end in sight. A victory could potentially come at a human cost so heavy that Russia won't be able to recover for decades. 200.000 dead young Russians today, that's potentially something like a third of a million less recruits available to the Russian military in 20 years.
Not that I think Russia is there, but it isn't an inexhaustible resource either.