You obviously haven't been following the money.
The statistical global marketshare of Firefox is very close to that of Internet Explorer --- within a single rounding digit.
https://www.bloomberg.com/news/newsletters/2023-05-05/why-go...
https://data.firefox.com/dashboard/user-activity
The most *easy* and sustainable way to achieve this is by using a fork of Firefox --- aka LibreWolf.
https://github.com/K3V1991/Disable-Firefox-Telemetry-and-Dat...