no there many russians who don't support war.
speaking about "russia" only just as it's president/government doesn't really define russia as a country, there's land, values, culture it's people and language any changes in government doesn't reduce or destroys these things.
This "existential thread" is fear of it's presidents projected on it's people doesn't really reduce/destroys it culture/values or reduce it's lands.
The highly hierarchical structure of the Russian society, is still reminiscent of a feudalistic society.
If you look at Russian history, ever since they were ruled by the Mongols, has become one where the leadership maintains it's power, by instilling a sense of discord and competition between the lower strata.
This way the ruler can have the lower classes fighting each other for his favors, instead of having them fight him.
Putin also does this, by having Generals competing with each other. And by having several military branches separated and competing among each others.
On the case of the people, most will never rise to even play at the higher levels. But the ones that do, are absorbed into this machine. If they don't play this game, they get left behind or killed.
There is also a current unwritten "agreement" between the Russian people and it's leadership. Where the Russians can do what they like to, as long as not to interfere and criticize the state. So basically, a separation between the state and the Russians.
And this is where the current war, can subvert this agreement. Because now, the Russian leadership is breaking this agreement by forcing the people to do what they don't want to do.
You will notice that a lot of Russians don't care about the war, as long as it does not affect them.
And remember that Russians have 2 different words for Russians. One only for ethnic Russians, and another for people of other ethnic groups.