The Afghanis nod in agreement. That’s how they chased the Russians out, at a time when the Russian military was a lot stronger than it is now. Took them a while, but they eventually did it.
Also, as Peter Zeihan points out, it’s one thing to take territory. It’s entirely another to hold it, especially when the population really doesn’t want you there.
Zeihan estimates that, given the level of Ukrainian resistance, it could take 2 million troops to hold Ukraine, and the Russians simply don’t have that. I don’t know what he bases the 2 million estimate on, but I sincerely hope he’s right.