I was shocked at how many of my Russian friends that I've known for 20-30 years actually supported the war at first. An ex of mine, from Ukraine, but Armenian, ultimately married a Russian/Ukrainian (parents were split) and then they moved to Canada. Two months before the war, for some reason they moved to Russia and were happy as heck when the war started. I was in utter shock to put it mildly.
As I mentioned upstream, Russia did quite a good job of controlling info into the country. So even people that I thought were fairly well informed weren't really aware of the atrocities going and what such bull crap Putin was spewing. The problem was, a little truth in the lies goes a long way. A perfect example is using the Azov Brigade as evidence of Nazis in Ukraine. Yes they were neo-Nazi groups. There also a lot of right-wing groups in Russia as well.
I remember being in St. Peterburg, and the skinheads would get on and start beating the crap out of anyone not white who was on the metro. They were covered in swastikas and other Nazi symbolism. So if Putin was worried about Nazis, he should have started at home, in the city where he rose to power. So, the little truth in the lie made it very easy to swallow for many Russians.
Now, many Russians have realized the war is a mistake. Now it is too late to really do anything about it, not that they had much say. Even though they realize it is a mistake now, they sure as hell don't want Russia to lose either. They are a proud people and their ability to endure suffering would send many Americans run crying to their safe spaces. I was always amazed when living there with what crap the average Russia was willing to endure on a daily basis and just get on with their lives.
I wouldn't underestimate the Russian people's will to hang in there even if it looks like there is no end. They've endured some horrendous wars and leaders and somehow survived. They are a very proud people at their core.