Don't mistake popularity for ubiquity. Microsoft made its fortune on corporate clients, and since people would copy software to use at home, it was easier to buy the same system in a lot of cases. Plus all the clone price wars other comments have mentioned. Microsoft got where it is because Compaq got away with reverse engineering IBM BIOSes, etc. It's all interconnected.
I was relatively fortunate as a child in the 80s to have access to lots of computers, we had everything at some point. But my mum can easily remind me that the money we spent on computers was money not spent on vacations or travel. I was the DOS kid and the gamer, and my older brother hacked Macs.
I started with a $2500 Apple ][+ kit, which made it easy to transition to MS-DOS. The first school I went to used Commodores, and my first video game console was an 8-bit Atari with a keyboard. Games for the Mac Plus were pretty good, but once EGA hit and Sierra and Lucasfilm Games caught on, that's where my attention went. Stuck with PCs and Windows until I decided to give up building/upgrading them in 2005, but I knew DOS and WFWG311-Win95-98-2000 like the back of my hand. It was useful.
Never got into OS/2 or anything like that. Loved the commercials tho. "
Oh-es-dvie-varp!"
Once Apple had Intel chips and Bootcamp, it didn't matter what my hardware was. Games run fine, and I prefer OSX for being productive. I no longer need low level access to my boot sector, FAT tables, or interrupt hooks. I like to do things
with technology, not
to technology.
😉