If Russian troops had entered Kiyv with cheering crowds of Ukrainians throwing flowers at their feet, if they had taken the Ukrainian capital in three days, five days, or even a week, as they expected, Russia would have won. If Europe and NATO were so divided they were paralyzed to do anything about it, Russia would have won. But it didn’t work out that way.
The West took a very long time to react, but it is already sending truckloads of weapons to Ukraine for the fighting. In addition, Ukrainians have been working up until now to create a modern, well-trained army in response to the impending Russian threats since the 2014 aggressions. The many years of fighting in Donbas provided them more than 400,000 (of which only half were active at the outset of the war) battle-hardened veterans.
Even with the small gains recently made at Bakhmut at the cost of heavy losses of materiel and personnel, the Russians are thus far losing the war. The fact is that more than a million men have fled the country. Vladimir Putin has lost more than 120,000 soldiers killed in action, not counting the wounded and disabled, he's running out of missiles and has had to resort to a third-world country to replenish his forces with inferior missiles and drones from Iran, his flagship and several important warships have been sunk or heavily damaged, he could not take Kyiv and lost other important cities previously occupied, he's lost large areas initially gained, his economy is starting to spiral down, oil and gas exports to Europe have plummeted, Western armaments continue to flood into Ukraine while he relies on rusty old tanks from the 60s, and he's had to resort to the draft to fill his trenches. But even that is failing and he has been forced to resort to mercenaries.
Mercenaries fight for money. They require substantial payments to serve. If the amount of money is not attractive enough, they will not fight. Russia is spending vastly more than expected and the funds available for the war are not enough to maintain an entire army of mercenaries, probably no more than a few thousands. History has shown that mercenaries always are brutal towards civilians, commit many war crimes and never perform well against trained opponents. However, they are performing much better than the demoralized Russian soldiers who are realizing that they are not defending their country but attacking a hitherto peaceful neighbor.
The serious problem facing the Ukrainian strategy is that its allies prevent it from attacking the enemy's supply lines and depots inside Russia for fear of a much bigger conflagration breaking out. Therefore, it is very difficult, if not impossible, to win a war when the enemy enjoys a practically inviolable sanctuary. But there is a high probability that Russian forces will be further demoralized and depleted amid an economic and political collapse that could cost Putin his job and get the Russians to seek a ceasefire and a negotiation that might allow them to keep Crimea.
Russia started the war to prove its military might and ability to bring NATO to its knees and annex Ukraine without suffering serious repercussions. Very likely as a first step toward annexing Georgia and Azerbaijan in the Caucasus, among other expansionist goals the Russian dictator may have in mind.
They utterly failed. The Russian military operation has been a massive disaster from day one and they haven't really sorted themselves out yet in spite of the limited advances in Bakhmut. Everyone around the world now knows that the vaunted Russian war machine is a sham, a paper tiger, that is doing its utmost to seem fearsome with threats to unleash an absurd nuclear war.