The further you pull a rubber band back, the harder the snap.
When I was a kid, the Vietnam war was going on. Of course, we were the good guys, at least in the mind of an 8-year-old. I wasn't aware of the nuances of the war - for example, that we were propping up a minority (and corrupt) Catholic regime in a country that was overwhelmingly Buddhist. Stores were spread about the "VC" jamming chopsticks into the ears of Catholic Nuns and Priests - stories about as truthful as "They're eating the cats, they're eating the dogs!"
But we wanted to believe as we were the good guys, saving the world from the Nazzies and Hirohito, and pushing back Chinese aggression in Korea. Hooray for our team! Every person on the planet tends to believe this about their own country. No one wants to think they are the bad guy.
And we aren't bad guys. But sometimes every country does dumb things or even evil things. It takes a while for people to realize that, "Hey, that was a really shitty idea!" and in some cases, some people never figure it out. There are people today, in Germany as well as other countries, who think Hitler had the right ideas and "if only..." things would have worked out OK in the end. The fact that they didn't never seems to register with those folks.
With Vietnam, the first inklings that something wasn't right came from the youth who were being drafted, who wondered why their lives should be interrupted - or ended - to fight in someone else's war on the other side of the planet. Incidents such as the My Lai massacre created more doubt - although even then, we tended to rationalize those things as "a few bad apples" and thus forgot about it.
We overthrew the corrupt South Vietnamese government and replaced it with one just as corrupt, and failed to notice that the side we were championing was not even popular with the people they governed.
Every evening, in 1968, Walter Cronkite would tally up the dead in a "body count" graphic, and every night, it would be like 257 VC dead and 15 American dead. We had to be winning! Eventually they would run out of soldiers, right?
Over time, we dropped more and more bombs - more than we dropped in WW2! And Agent Orange, mining harbors, and so on and so forth. The mightiest Army - and Navy and Air Force - were brought to bear against the guerrilla army of a tiny Southeast Asian county (admittedly, supplied by outside forces) and at best could fight to a stalemate.
Some in government started to realize there were limits to our power. Short of using nuclear weapons or firebombing cities, we could not "win" the war, and even if we did, we would lose in the world political sphere. After nearly two decades, we called it quits and went home. Shortly thereafter, the North Vietnamese took over and today, oddly enough, don't seem to have too much of a grudge against us, even as we poisoned the land, left unexploded ordinance, and killed millions.
In retrospect, it seemed like a stupid idea - taking over a war that the French had lost, on the pretext that somehow we were preventing the spread of Communism. Not only did we fail in Vietnam, we tipped over the dominoes in Cambodia and Laos. One wonders whether we could have done better by embracing the North Vietnamese - as we eventually did - rather than opposing them. Today, they are a trading partner, and they use us as a wedge between themselves and China.
But still, today, just as there are those who think Hitler was right (and in Japan today, Tojo), there are angry veterans who still believe that "if only..." we could have won in Vietnam. Hey, we have people still fighting the Civil War - in their minds. But for the majority of people, the writing was on the wall - it just took us two decades to read it.
The Soviet Union went through the same thing in Afghanistan - and we did as well, decades later. Our adventure in Iraq accomplished nothing, other than to embolden Iran - leading to the chaos we see in Sudan and Palestine and Lebanon today.
It seems when you invade another country, you eventually lose. Unless you are willing to bomb their cities into rubble and - as Churchill once put it, "make the rubble bounce" - you can't win. And even if you go that far, as we did in Germany and Japan, you can't hold onto a foreign country for long. We let the Germans, even ex-Nazis, particularly ex-Nazis, take over control of "West" Germany after the war. We allowed Japan its independence, as we realized an occupying Army could never control the country. Even so, of course, we have military bases in those countries today.
We seemed to forget those lessons when we invaded Iraq and Afghanistan - as did the Soviets with the latter. And Putin may be failing to appreciate the past as well. But the average Russian? Again, it is natural to assume that anyone residing in a country may be inclined to root for their home team, particularly when the propaganda shades their view. Just as we read the "body counts" every night in the news and assumed we were winning, I suspect Russians are reading similarly biased reports on their news channels and assume that, any day now, Ukraine will collapse. Sure, Trump may cut off aid to Ukraine, but Western Europe may fill in that void, as they rightfully should, as the war is on their doorstep.
Russian people turned against their own Afghan war when bodies started coming home in bags and the cost of occupying the barren nation started to degrade their own economy. Putin seems to be keeping dissent in check, through propaganda, lengthy prison sentences for dissenters, and defenestration. But this only stretches the rubber band further.
Having your son or husband come home in a bag is disheartening. Having them listed as "MIA" and left to rot in some field - so the Army doesn't have to pay death benefits - is even worse. Eventually, something has to give. But it could take a long, long time before that happens. Remember we were in Iraq and Afghanistan for two decades before we bailed out, realizing there was nothing more to be gained by staying, and we had gained nothing by going in the first place
Can Ukraine last that long? One wonders. Even if Russia "won" could they survive decades of insurgency? How long can Putin - age 72 - realistically live, or be fit enough to lead? Will the next leader be willing to continue an unwinnable war with Western Europe?
Hard to say, other than in the interim, a lot of people will suffer and die for no apparent reason whatsoever.