I wonder if they just became terminally risk averse.
The thing that made them big is pretty obvious: high-margin premium priced x86 CPUs, which is a position they were able to hold for decades due both to manufacturing excellence and being able to shepherd the standard. They simply can't do it anymore-- execution has stumbled, and the market for x86 is gradually weakening, especially in spaces outside the cut-throat, lower margin, consumer/corporate desktop "it must run Windows and my line-of-business software/Call of Skyrim" vortex.
They could have been using decades of margin to build and consolidate positions in other segments of the market, just to be sure that the next clever new device comes out with an Intel chip, even if it's non-x86. They didn't.
Rather than, say, taking the ARM licenses they ended up flogging and building a competitive mobile CPU on their leading process, they invented weird Atom chips that ended up in like 3 phones.
Okay, flash is huge now, but it's a low margin game maybe not worth their investment. But they chucked out Optane, which still had some possibility as a "halo product" and for some commercial price-is-no-object markets.
It remains to see how sticky Arc graphics will be; they got a boost by the tight market conditions last year where people would grudgingly take any card they could afford. Will people come back to them out of explicit preference? I also wonder if the Larrabee/Xeon Phi adventure set them back or ahead-- trying to make a GPU architecture out of x86 was an interesting take on "GPUs are hard to program", but did it yield a lot of useful knowledge?