Russia’s military is obviously stronger than Ukraine’s, but almost everyone is treating a total Ukraine military defeat, relatively quickly, as a foregone conclusion. I’m not so sure. Invading a very large country is hard, and Ukraine’s terrain in February is not exactly trivial. There are many instances in history in which a smaller defensive force has held off a larger attacking force for quite a long time. Active combat could drag on for weeks or months (or maybe longer).
We’ll see. Best wishes to Ukraine and its defenders.