Which geopolitical experts are you following that claimed Ukraine would fall in several days? I know of no one who claimed that. From what I can tell, this idea that they would fall in a few days was created in mainstream media due the kind of warnings being given by Washington about Kiev being attacked and backed up by popular imagination of Russia being a superpower.

A lot of experts who said there would be no invasion were wrong, I'll give you that. People were and are still puzzled and debate over why and whether "phase one" went so badly.

But I do recall reading predictions about Russia not having the kind of air superiority that people think they do and that they would not use air power in the way people expected them to.

Finally, when talking about this, it'd be better to first define what a "loss" and "win" would be for Ukraine and Russia.