Brave’s market share seems to be siphoning off Firefox users primarily more than Chrome’s…
But not as great as how fingerprint generalization works in a hardened Firefox[0].
I guess I'm one of those people.
I was on Firefox because I refused to use Chrome, but Chrome is the de facto standard whether I like it or not, so I was always open to switching to a Chromium browser that didn't suck.
I tried Vivaldi for a while, but it was obvious it was never going to grow beyond a very niche user base. I tried Brave a couple years ago and it wasn't quite ready. I tried it again last year and now it's my main browser.
Without getting into any technical talking points, there's definitely a market for "Chromium browser that cares about privacy and actually has a decent share of the market". Whatever you think about BAT or Tor support, they brought in a critical mass of early adopters.