And how Bill mom (IBM board member) helped him to win the contract for... IBM, despite better options on the market. Thanks to that we were all rewarded with such gems like Windows 98 ME or Windows Vista.
Microsoft has been crucial into bringing compute in people's homes, the evolution of video gaming, the internet etc.
They fluked a lot, they used their advantageous position like most companies try to, but assuming that we would have gotten better alternatives is not a given.
Also, in hindsight was IBM wrong to bet on Microsoft? They sure have done multi hundred billions $ together.
And it's naive to assume that other companies wouldn't have used the same tactics that Microsoft did.