To be fair, russia losing this conflict outright won't necessarily prevent it from happening again. Or at least I don't see how this would be a guarantee of such a thing. Will putin stay in power in this scenario? Does he get replaced by someone worst? Will russia continue to regard ukraine as part of the russian world? How will defeat affect russia's "security concerns"? In the extraordinary scenario of an ukranian victory I don't think any of these questions has a clear answer.
When I say losing, I mean that Russia has to admit defeat and pull out of Ukraine completely. I think in that case, Putin would have to go, too, but not because the west forces him but because he loses grip on russia.
While Putin then might get replaced with someone worse, the Embargo will prevent Russia from regaining its military strength. They cannot recover easily from losing all these soldiers and equipment.
The nukes would keep being a problem, but the capabilities of the russian military would be severely limited. Furthermore, after this clusterfuck, there is a push in eastern europe for nato and EU. If that is successful, Russia does not have any real targets to attack anymore.
Even for the most ideologically brainwashed societies, there is a time for reality to sink in. When there is no russian Donbass, no russian Odessa but many dead russian soldiers in a month, in two month, and the russian wealth spirals further down, i do not think support for this war will go on for very long.
It is one thing to be pro war when it is a special operation that only your russian supersoldiers do, kill some nazis in kyiv and come back home. It is another thing when more and more young russian men from middle class families get drafted without any apparent success.
In my opinion, every even small russian success prolongs the war while a series of defeats shorten it. It is true that russian civilians are a problem, because they are afraid of russia losing and what will happen then. I agree that the west needs to do more to directly speak to russian people and make it clear that sanctions will fall and aid will come should russia withdraw.
But that can only happen after there is no russian soldier left in Ukraine, and to me, ukraine winning means russia withdrawing out of all of ukraine.