I believe the EU as a whole has actually put more into this than the US has (or it's extremely close), and not just in terms of the cost of taking in millions of refugees, but armaments, money, other aid, etc., If you get into individual countries' GDP numbers, some European countries are punching well above their weight class, especially the smaller countries.
The US is actually spending very little, especially when compared to our defense budget, and if you want to look at it in a cold/rational manner, every bit of Russian hardware that is destroyed in Ukraine, is Russian hardware that won't end up in some other part of the world, presenting a future threat to us or our markets, as well as diminishing Russia's ability to fuck around elsewhere.
Oh, and a whole lot of the stuff we are sending over was sitting in storage or slated to be replaced/surplused. We have thousands of Abrams in storage, thousands of Bradleys, thousands of M113s, thousands of Humbles, just sitting there, doing nothing other than costing us storage/maintenance, because we drastically reduced our military in the 90s after the Soviet Union collapsed, or we have newer systems on the horizon - they are all slated to be replaced, but we keep them in storage "just in case" even though we couldn't ramp up the US military fast enough to actually man and use them.
And we do this not just because we present ourselves as leaders of the free world, but because we are Europe's largest economic partner, and we export hundreds of billions of dollars of goods and services to the EU every year. It's the same reason why we have such a massive military, such a massive Navy - world stability is good for our markets.
And we damn sure don't want the Russians controlling so much of the world's food supply, because they can cause instability in South America/Africa due to rising food prices, and in the case of South America, that will drive people to head for our border.
Europe is already putting a lot into repairing infrastructure right now.
Stop listening to Russian and Chinese propaganda, we are not hurting our military readiness in terms of China. It's a completely different scenario, for a lot of reasons, including that we are not sending our best stuff to Ukraine, and especially because of that whole water thing. China simply doesn't have the military built to cross 100 miles of open, hostile water, with a very limited selection in terms of landing beaches, all of which are easily defended. For fuck's sake, they are relying on civilian cruise ships as troop transports - those fucking things throw off a radar signature that would be seen from Taiwan. One Harpoon would put thousands of Chinese soldiers on the bottom of the ocean. And the Chinese military would have to make a lot of trips across that 100 miles of open water, and as they lose more and more amphibious and landing support ships, they would need to make even more trips with the remaining ships, and it's just a fucking nightmare for the Chinese. There's a reason why we did Normandy the way we did, and why we planned to invade Japan the way we did, and China is doing none of that, and they have to face modern weapons that can hit over the horizon.
It's like German threatening England in WWII - they only had fucking river barges, which would do them no good crossing the English Channel (and they'd probably have more of those barges swamped on their own than destroyed by the Brits).
But wait, there's more. The US alone, if we didn't step in to help Taiwan, just our cutting off trade to China if China tried, would completely destroy China's economy and put hundreds of millions of Chinese in the streets, and would put them on a crash-course to starvation and mass chaos, which their military is not large enough to handle. The Chinese made the mistake of relying too heavily on us.