I think what they were trying to say is that, to the kind of mind capable of being as ruthless in getting to the top as Gates was, the biggest anxiety they would have after making it to the top is that someone will come and take it from them.

Market cap during the Steve Ballmer CEO tenure would be a better comparison, as it was during this time that MS was fighting Blackberry, Nokia, Apple and Android on the mobile OS front. This was the battle that Gates was worrying about: the declining prospects of Windows as an application platform.

Their stock exploded once Nadella came in, killed off DOA products like Windows RT and Windows Phone, and shifted the focus to Office 365 and Azure cloud where they had a deep enterprise advantage.

How does that disprove my statement? Microsoft essentially had a monopoly on desktops and software in 1996. Just because their market cap is larger now doesn't mean they weren't on top in 1996.

Does anyone really think Microsoft has as much influence on tech today than they did in 1996? They've clearly been pushed out by Google, Apple, etc, which is exactly what Gates was fearing would happen (although in this instance, the threat he feared was from Java/Sun).