>A sunk cost fallacy is only applicable if the assumption is the venture would result in failure.
The sunk cost fallacy is not really about what the venture would actually do. One could be said to have fallen prey to it even if they double down and the venture eventually succeeds.
What's important is that at the time of the decision (a) the path doesn't seem to be working, and (b) they think "but I've spend too much to quit now".
This is more likely when one assumes it can still has a chance to succeed, than if they assume it will inevitably result in failure. Nobody that assumes inevitable failure would decide to continue.
I did not feel it needed to be specified since it is a trivial fact that nothing in life is certain. But Apple's product offering is a top to bottom customer experience involving in person help at stores around the country. Microsoft must have acknowledged that, since they went as far as opening stores and coming out with that line of non malware Windows products (as a side note, it is ridiculous that Microsoft even let their ecosystem get to that point). Which, yes, they might have had empty stores, but that is because they failed to continue investing in their mobile products, or even non mobile products. They would have had empty stores for 10+ years while they slowly build it all up, just like Apple had to.
All I know is at this point Microsoft had two options: continue investing into creating an alternative to Apple, or cancel their plans and sit back and let the Office/Azure revenue flow in.
Maybe it was a long shot, maybe they decided the size of Apple's customer base divided by two was not enough to satiate them, but whatever the case, they signaled that they do not have the talent/gumption/appetite for risk to pull it off. But if any company did have the opportunity to go for it, I would think Microsoft (and Google) with their income stream would have been in position to do it.
Both companies seem to dip their toes, but never follow through.
