Even in this case though, I don't think it means anything more than "we were so used to using our monopoly power to steamroll everybody that we expected to keep on doing that". Microsoft only ever dominated the personal desktop computer OS market. They were a minority player in server OSes their whole existence, losing first to big iron and later to Linux. The handheld market went from being owned by companies like Palm to Apple and Google dominating. I know less about the embedded market, but Microsoft has been trying to own that for 20 years, and I don't think they've ever had a dominant position. I think even their desktop OS dominance was less to do with Windows being an amazing operating system and more to do with it being the thing that ran Word, Excel, and other popular business software.
So I think tsunamifury is right. Gates got so comfortable winning he saw it as "natural", rather than a combination of luck and their willingness to be an aggressive monopolist in a newfangled industry and during a period where antitrust enforcement was falling out of vogue.
It might be natural for the NY Yankees to win a world series. Some people complain about it when it happens. Some people don't like the Yankees. But they are pretty good at baseball. When Microsoft lost the mobile market, it was an unfortunate thing for them.
Bill Gates doing his postmortem relent on losing that market is not a big deal. It's just what you do when you take a loss.
You ever lost at anything you've strived for? It's hard not to think about "what if"? That's very human.
I agree it's "natural" (by which I mean common) for people with systemic advantages to pretend that it is "natural" (by which they mean expected and correct) that they continue to receive those advantages whatever their actual merit. It's natural, but also revealing of the individual in question. Because not everybody does that. Just sticking with tech titans, we have Steve Jobs" and "stay hungry, stay foolish". And Andy Grove's, "only the paranoid survive".
I also think "not a big deal" is thoroughly wrong. Had Microsoft not gotten fat and arrogant on monopoly rents, they might have done a good enough job making OSes that they wouldn't now be struggling to stay relevant.