2 reasons imo.

1. Chrome inertia. Everyone who’s locked into it from the days it was legitimately faster.
2. Every time it gets mentioned, its supporters like to “no true Scotsman” the original project and suggest their preferred fork instead.

I think being the only browser with a credible stance on ad blockers will help them in the long run.

Most people on their phones use the default browser, either Chrome or whatever Chromium-based the manufacturer includes. But otherwise it's the browser included with the Facebook app, as some are literally locked into the Facebook-and-Youtube walled garden.

I use it and I install it on every family and work PC I can but the memory of the bloated Firefox that made so many originally switch to chrome is still there. I want apple to base their browser on Firefox to maybe get some traction back

Im gonna be honest, im glad a lot of people don't use ad blockers, or they would come down a lot harder on ad blocking. As it is google is trying their hardest to push their authentication nonsense everywhere to lock us all in to whatever software THEY decide we are authorised to use

lots of people don't like the direction the company is heading