Well Firefox is largely the default on Linux, so it wouldn't represent a proactive choice. And linux users are probably more likely to fall into the category o

Well Firefox is largely the default on Linux, so it wouldn't represent a proactive choice. And linux users are probably more likely to fall into the category of sophisticated user than the general population. I don't see any evidence in what you've presented that the average computer user cares at all about what browser they're using beyond "I will click until the annoying notifications go away".