It has been, and still is, none of America’s business.
Apart from kickbacks of billions of dollars to corrupt American politicians, Ukraine is of no strategic importance to the USA.
U.S. taxpayers gain NOTHING from pouring vast amounts of their money into keeping the slaughter going until the last Ukrainian is killed.
You are correct. But neocons disagree with you. Neocons love foreign wars even if it means it is on borrowed money.
How many BILLIONS we have squandered in Iraq, Afghanistan, Libya, Kuwait, etc? And what exactly was the benefit to US tax payers? Oil is fungible commodity. Those countries have no other use for oil except sell it. They can not drink it.
So to quote Hilda beast, “what difference does it make” who owns the oil? Even Venzuela is selling us oil.
The US deep state and neocons see Russia and China as the only strategic competitors to total global dominance. Of the two, Russia is actually more "dangerous" because its both a European and Asian power. Its a military and resources power. I would add its also on Europe's doorstep, and is also now promotes its Christianity (whether fake or real), which is a competing western world-view to financialized, woke-globalism. Everyone talks about the 2019 RAND report about hobbling Russia, but it goes back decades to Brzezinski and Kissinger.
So for those people, containing and dismantling Russia is of absolute importance. Its why they have been active and interested in controlling Ukraine and pulling it into NATO, since Putin arrived on the scene.
Russia's invasion made it strategically important. Putin planned on this being a fairly painless episode leading to the annexation of most of Ukraine with maybe a rump puppet government in Kiev. In the absence of any significant opposition from the US and Europe, he would then have moved on to other tasty morsels like the Baltic states within a few years.
Preventing that from happening and making Russia's defeat clear are now very much in the strategic interests of the US.