Speculation on my part but i think it’s the same thing as Boeing really. They didn’t have any real competition for so long and they started cutting out the engineers who innovated to improve stock price.
There used to be a saying that Intel had a vault where they paid out the next ten years of CPU tech, so when they invented something new they put it there so they could make profits and control the advancement.
Now, I’m not sure which thing they got wrong, but if it was true, I think Intel was probably caught off guard by all the speculative execution security issues and the GPU revolution (blockchain and AI).
I’d say they just didn’t go touchscreen in time I remember a friend having the first iPhone and another had a Nokia n95 The N95 was way ahead in features and technology but people wowed over the Apple screen…
They also did other weird decisions like focusing on Symbian, and then move all their attention on Windows. Nobody cared about Symbian or Windows. Everything was on Android and iOS.
They were too slow to adapt to the new market, and when they adapted they did so in the wrong way.