https://www.netmarketshare.com/operating-system-market-share...
According to a few sites, Apple has between 5 and 10% market share.
Windows still absolutely dominates the desktop market, with Mac, Linux, and other *nixes picking up maybe 15% in aggregate.
But I believe the poster was saying that Apple is now a titan, which is true when you look at mobile devices (which now dwarf PC sales in terms of raw numbers). Microsoft has been failing in mobile for years, which makes the old Apple-Microsoft rivalries seem quaint.
The Mac itself, though, has become more aspirational in society in general. It doesn't have the market penetration because Apple prices itself out of the the lower end of the market, not because its OS, hardware (hello one button mouse) or software range is sneered at, which used to be the case.