Ukraine's population is 40 million, but why can it managing to resist Russia with a population of 144 million
Better trained and motivated troops the same thing happened with Russia in the 80s when they went into the middle east. The same occured when America went into the middle east in 2001-2019. Despite having the superior numbers and military power and technology. Having the home field advantage of knowing your own backyard will always keep you a step ahead. Soldiers win wars not fancy tech if this were true how come iraq and Afghanistan aren't the 52nd and 53rd state of the usa right now? Ukraine was holding Russia back with quite primitive stuff before the usa sent them javelin atgms . An RPG 7 is a "you see that tank over there?" I don't want to see it anymore." And those are dumb fire weapons a 5yr old could shoot.
The only way to win a war without troops is to nuke it or bomb the place until its nothing but a crater. War is just as much about resources as it is defeating a threat, there's no point if you don't gain anything out of it profit wise.