In spite of its dwindling usage, Firefox is still used by more than a 100 million people on desktop.
I posted this comment some days ago [1]:
To put some numbers on what a 2.54% market share means, Firefox actually tracks this data. See here: https://data.firefox.com/dashboard/user-activity:
> Monthly Active Users (MAU) measures the number of Firefox Desktop clients active in the past 28 days.
> February 10, 2025: 163,203,913 clients
> February 17, 2025: 163,742,671 clients
1: https://news.ycombinator.com/item?id=43219572