I use Firefox personally and originally made the thing for myself. I added Chrome support because Chrome is much more popular (not far from ten times more popular these days :() and people I would like to use this, eg friends and family, mostly use Chrome.
I couldn't ask them to switch browsers for my little side project. I have to co-operate with Google's bureaucracy. For what it's worth, so far it seems like Mozilla is not exactly streets ahead, but at least they didn't charge me and they seem to be fairer and more helpful to extension developers (they have a "self-distribution" mode with relaxed oversight I used while in private alpha, and their tools and docs are better).
I think it would be perfectly reasonable to promote Firefox to your friends and family as "simply the better choice" irrespective of your own interests.
When Chrome was better, I suggested friends and family use Chrome. Now I think most people would benefit from using Firefox as their primary driver.
Are you including the change cost here, which will be many times higher for most of the population vs. HN? Even if I thought that Firefox was a better choice, I'd recommend to my friends and family to keep using whatever they are using unless they have to switch for some reason.
Lazy web devs that only test in Chrome and maybe safari that constantly break things in other browsers. I don't mind sending the angry support email and using chrome for a single task here and there but others might.
Bank of America didn't work for the better part of last year. Chase Rewards are currently broken since last week. Its easy to drop small sites that don't test but my experience has been they actually bother testing and it's the major sites that actually have problems.
I've had Firefox fail to work properly on the sites of Slashdot, Amazon, Newegg, Chase, BoA, GE, Walmart, the IRS, PennDOT, Mozilla's own org site, WaPo, NPR, Fox, Disney, and a whole host of others.
I think this is because programmers have very specific and personalized workflows for all the tools they use so they assume other people are the same way when in reality a browser for most people is just a tool to get what they want.
I couldn't ask them to switch browsers for my little side project. I have to co-operate with Google's bureaucracy. For what it's worth, so far it seems like Mozilla is not exactly streets ahead, but at least they didn't charge me and they seem to be fairer and more helpful to extension developers (they have a "self-distribution" mode with relaxed oversight I used while in private alpha, and their tools and docs are better).