I know right? :D That always bothered me as well.

In the novelizations it was written that Skynet could not adapt to humans not running away or not vacating territories after they have been defeated. One of the quotes was: "Apparently it underestimated something that it kept analyzing even now: the human willpower." I've read this as Skynet not being able to adapt against guerilla warfare -- the hit-and-run/hide tactics.

But the TL;DR was that Skynet was basically playing something like StarCraft as if it played against another bot, and ultimately lost because it played against humans. That was the "Skynet was not creative" angle in the novelizations.

This is a complete tangent but:

In Terminator 1 Skynet looses because John Conner taught people how to fight the machines, but John Conner only knows this because Kyle Reese taught Sarah Conner how to fight the machines and she taught John Conner. But Kyle Reese only knows this because he was taught by John Conner- so there's no actual source of the information on how to fight the machines, it's a loop with no beginning or end.

I had a philosophy teacher who said this is evidence of divine intervention to destroy Skynet, essentially God told people through John Conner how to win, but a cut scene in Terminator 1 implies Skynet was also created by reverse engineering the chip in the destroyed Terminator- implying there's also no origin of the information on how to create Skynet and it's also an infinite loop.

Yeah, these discussions are fascinating but I'd still think it's not very hard to learn how to blow stuff up and sabotage assembly lines, given enough tries.

So it's not exactly an infinite loop IMO, it's more like that the first iteration was more crude and the machines were difficult to kill but then people learned and passed the information along back in time, eventually forming the infinite loop -- it still had a first step though, it didn't come out of nothing.