You can have a monopoly without having 100% of the market. Even one of the most famous monopolies, AT&T throughout the 20th century, never had 100% of the market. You know this, so now you're just actively lying.

Microsoft was briefly deemed a monopoly by engaging in anti-competitive practices and abusing its market leadership to squash competition, like artificially blocking the use of DR-DOS to install Windows [1].

[1] https://en.wikipedia.org/wiki/AARD_code