This is basically simplistic worldview for those that want to hear this kind of a talking point.
Therefore lets go one by one.
1. This war happened because Russia ambitiously rolled all of it's military might into a country of 43 million people. Which decided to resist by any means possible because otherwise they would cease to be a country and they will probably be culturally assimilated.
2. It is almost funny how no one thinks how much Russia got crippled by this. Losing access to global markets so that they have to smuggle stuff around. They lost most of it's modern military equipment and they wouldn't replenish that anytime soon. They lost huge European market for their energy and they can't cover that hole since others don't have the same purchasing power. Not to mention that the infrastructure for switching customers isn't there. They also lost the Baltic sea to the west since Sweden and Finland are joining NATO. Plus it seem they are also losing Moldova and Armenia in real time. As a matter of fact the EU is more united than ever since all of this is a slap that was evidently needed for people to wake up. There is still some Russian influence in the mix but that is being cleared out in systematic manner.
3. Also about which decline of European economy are we talking about ? I will have about 2.5% growth this year, while inflation made by energy shock is melting. What is in decline is Germany which made some really stupid decisions, like closing it's last nuclear power plants in the middle of the war with it's main energy supplier. You really have to be extra smart to do that. But that isn't Russia's fault. Plus I have to say that all of my local assets controlled by Russia where frozen and they got nationalized, what is a huge deal because in one move we are getting rid of Russian influence through economy. What is basically the real end of Communist era and my local comrades in Central Europe are in panic mode over that. They are even cursing at US for crashing their world (the local comments are full of that). What is because everything that is Russia related is drying up, and the process is almost over.
4. While the whole "decline of the west" thing is mostly because it refuses to clean up it's own house and Russia has little to do with that. Plus since the whole western public is pushing this "decoupling from China" narrative it can be said that all of this is the consequences. The supply chains have to be remade down to the last detail and that will surely rise costs and inflation. Since replacing China is a serious challenge that is anything but cheap.
I am simply tired of the talking points that the west is losing in Ukraine and it has to give up. What should have been 10 day take over has turned into a complete holding of Russia. Since after 600+ days of war Russia has only about 17% of the country (and half of that they got before the big push last year).
Note to self: You should really search for a job in some neo-con think thank. They would pay you well for this.