https://nestcentre.org/the-unknown-toll/Fairly recent article regarding trying to estimate the number of Russians killed in Ukraine thus far.
Even the most conservative estimates at least partly verified through obituaries and other independent sources has 110,000 - 150,000 killed as of June this year (first 40 months).
United States lost 58,220 killed in Vietnam War over about 10 years. Russia appears to have lost at least twice that in a third of the time in this 'Special Operation' but I think that is often shrugged off as just some Russians from the most expendable part of the population bring sacrificed for the good of the Motherland. Like a bunch of meaningless worker ants getting squashed to protect the Queen.
No democratically elected government would be able survive such enormous cost, but Putin's totalitarian grip means he can continuing driving Russia through this quagmire and throwing away Russian lives for a long time if that is his wish.
Russia has set the conditions for a 'Forever War'. Putin has clearly stated the objective is regime change in Kiev and a disarmed Ukraine. Complete surrender as an independent country.
Which means a significant portion of western Ukraine population will fight to the bitter end as an existential crisis, which means the current and feared increased refugee crisis and fears of additional Russian aggression will drive Western
Europe to continue supporting Ukraine, and which means U.S. will have no choice but to in turn support Western Europe due to huge economic and military ties with those fellow EU and NATO countries.
This won't end until Putin and Russia tires of the 'Forever War'. Who knows how long that will be because Putin has seemed to have somewhat boxed himself into this being an existential issue that all of Ukraine must be taken.
Paradoxically, the best way to end this 'Forever War' is to make it crystal clear to Putin and Russia that there is no end in sight. A 'Forever War' it definitely is. Has to be crystal clear that Ukraine is never going give up and that Western Europe and U.S. are never going to stop backing them. And through sanctions and tactics and support, you make the 'attrition' process as costly to Russia as reasonable possible.
And hope eventually Russia recognizes there is truly no identifiable end to it and fatigued by the cost is finally ready to negotiate.
Won't surprise me if 5 years from now, this thing is still hot. Might take at least several more years until this thing simmers out. We'll see. At a Horrible horrible cost to both Ukraine and Russia.