The issue here is, at a economic standpoint. US did not lose anything they had not allocated. Bear in mind, all the budget were there, and in most case, it's a "use it or lose it" situation. And we aren't talking about getting in extra hundreds billion a year (it would be 300 billions a year for Iraq and Afghan combine) we are talking about 40-50 billions a year. That was well within the budget even if we are talking about extra allocation.
The economic impact can only be applying once, it's not ongoing because once you cut off the Russian (Which most EU did) it won't have a lasting impact on their economy, in fact, in most EU case (beside Eastern Europe that heavily deal with Russia before the war) have largely going back to pre-war level, oil price has gone back to $85-89 a barrel and inflation rate had dropped back to 3 to 4 %. The economic impact wasn't at that stage and EU as a whole is more than enough to deal with that impact. You are talking about the biggest Economic group in the world...
While on the other hand, those European country (and USA of course) are simply giving old weapon away and brought brand new from the US and EU, just like the US Ukraine bill, up to 80% of those money the Allies patched to Ukraine was actually being spend within the US and Europe, so those money were actually going back to US and EU economy. And those weapon (older F-16, older Leo 2 Tank) are going to be replaced anyway, what this war did is just brought the schedule up.
Again, as I say. The west involvement with the Ukraine war is not as big as you think and what Russia make out to be. This war is not going to be enough to make a lasting dent in the US and EU, not with 50 or 60 bil a year rate, let alone depleting their power, if they were giving aid at the stage of depleting their own power, the west would have dump a few hundred Fighter Aircraft and a few thousand tank, a few thousand Artillery and SPG and a few thousand cruise missile, along with a few trillion dollars combine every year to generate service and compensation. Russia would have been defeated in Ukraine a long time ago......
Also, it's worth notice that US wasn't aiming at collapsing Russia, the US was aimed to diminish Russia as a regional power, and make it Chinese problem (like North Korea), if US want to destroy Russia, all they need to do is to raise their own oil production by 10% and ask Canada to do the same (which was the first and tird biggest oil production country in the world), then oil price will be below $50 (around 35-49) a barrel, Russia is going to lose money from extracting oil and you are talking about 400 to 500 billions for Russia, that's almost half their GDP. The problem for China vis-a-vis Russia is, a damaged Russia is no good for China, because it would become their economic burden, there aren't many resources Russia had, and China can take most of the resource Russia had China had it too (like copper, nickel, sulphur), you are talking about roughly 600 billion worth of oil, gas and raw material (Iron ore, cobalt mainly) . Even if you can digest them all, in exchange you would have to prop up the entire 1.5 trillion Pre-War Russia economy. That trade is always going to be deficit, and with Rouble being non-tradeable, which mean you will need to pump 1 trillion worth of Yuan into Russia every year in order to make it afloat. And as you said, China can't have a collapsed Russia, which mean you are forced to take that mess.