Firefox

I'd guess that:

• Google is a bigger brand that attracts many people as a lot of them are already using some of the company's products
• These other products are well integrated with the browser: browser history is shared across devices along with passwords and extensions
• Google advertises Chrome in the Google Search, it's a default search engine even in Firefox

Most people are not tech savvy and/or privacy-oriented.

One reason is that if you use Gmail, every two weeks appears a "y u no use chrome" nag popup that can't be permanently dismissed

Firefox on Android removed the feature to open local html files. No, I'm not interested in running a webserver on a phone for local files lol.

Switched to Vivaldi.

Back when IE was on top and Firefox was the best browser, firefox started to put a lot of bad updates, then chrome came, it was faster and firefox started to lose its marketshare, for while firefox only peformed well on linux, by the time quantum came out and it's performance was good on windows again, Chrome was already the new IE, but Google is way better at managing this leadership it than Microsoft ever was, the only technical problem it has is devouring RAM.

In my opinion, gecko being so tied to the browser is also a problem. There's a ton of browsers using Blink, that gives google a lot of control over how the web will evolve. Having other browsers using gecko that aren't Firefox forks would be great.

I've used Firefox for years and I love it on Android, but on my work laptop (MacBook) I really enjoy using Arc. The vertical tabs let me organise things better, the spaces let me isolate tabs properly in a visually pleasing way, and I don't really care for extensions on desktop as I don't really browse much outside of work. I also prefer chromium dev tools, though it isn't that bad to switch to Firefox's dev tools.

If Firefox adopts few features from Arc, both in form and function, I wouldn't mind coming back. I know sidebar exists which lets you have vertical tabs via extensions, but damn Arc does it the best so far, natively!

Edit: oh, another reason was lack of background blur effects for Google meet. It's coming soon I think (I filed it on bugzilla), but damn it was needed like 3 years ago.

For me, until all below are supported Firefox can't be my primary browser.

1. PWA not supported and only possible with FirefoxPWA. I can't rely to anything but native, Mozilla could break FirefoxPWA any time they want.
2. I use my browser for my multimedia needs and I use my own Emby Server. Firefox doesn't support mkv container and the most important it desn't support HEVC. Please do not tell me about HEVC royalties and how much Mozilla would have to pay MPEG-LA. Chromium based browsers have enabled hardware HEVC decoding and they pay nothing to MPEG-LA because the royalties have been already payed by my graphics card. Mozilla simply doesn't care.

Websites glitch out more often on Firefox. I had my favorite Mastodon instance not letting me scroll back up because of some weird jittering bug that only applies to Firefox for some reason.

Photoshop Web (Beta) only supports Chromium-based browsers, Descript only supports Chromium-based browsers (well, Firefox still seems to work but you're on your own), and many new webapps are only supporting Chromium-based browsers. Now, these are beta products, so that might change, but it seems unlikely. So I've been switching to Chromium-based browsers to use some of these apps, but I'd really rather not. It's the way everything is going, unfortunately.

A lot of developers target the web because it means they can have one codebase that is supported on multiple operating systems. Imagine how much harder it would be to develop a macOS, ChromeOS and GNU/Linux version in concert with the Windows version. In reality, some browser engines support more web features than others, and Google has by far the most resources to keep up with those standards. So Firefox is an afterthought. Google Chrome is on every operating system worth supporting anyway, so why bother supporting another browser? It's a lot less work and testing.

MDN is the best place to read about those standards, though.

I like Firefox:

• userChrome.css lets me make Firefox look like a GNOME program
• I much prefer the developer tools. Everything is a lot easier. I always use Firefox when doing web development.
• I can easily customize the browser. For me, this means having a separate dedicated URL bar and search engine bar.
  • The search engine bar lets me swap between search engines very quickly and keep my previous search terms for new tabs. Switching search engines is really annoying in Chromium-based browsers because you need to use shortcuts, and there's no autocomplete for shortcuts. It also doesn't tell you whether you typed the shortcut correctly, so you're guessing every time! It's really under-developed. The Android Chromium-based browsers are even worse. You can't change search engines at all when searching; you need to change your default engine. Firefox lets you search any search engine easily on iOS, and slightly less easily on Android.
• I can...turn off history? Apparently this is an amazingly complex feature that Chromium-based browsers just can't handle. The best you can do is clear it when exiting, but you can't just turn history off.

Okay, it's mostly the search engine thing, to be honest.

But Firefox still doesn't use the new GNOME thumbnail view when you're uploading files, for example...

I didn't find the performance gap really high when I switched from Chromium to Firefox. Even on my shitty old laptop, Firefox works fine. I have to admit though that it uses way too much memory.

I do agree with your 3rd point though. History has taught us that defaults matter a lot. Firefox isn't a default anywhere apart from linux distros and FirefoxOS was a failure.

If you've been on youtube for the past 6 months or so, there were a lot of OperaGX sponsorships given to large creators and a decent majority of people have used it, liked it, and started recommending it to others via youtube comments.

There's also the fact that chrome is the browser that, at least here, is the most well known at this point and is usually preinstalled on school computers, so this builds up familiarity.

And probably a smaller reason why is because mozilla itself - it hasn't been that great of a company and the firefox over the years has gotten somewhat worse and worse.

I still miss the print a webpage to pdf on mobile firefox.

I use Firefox. The only thing I don't like about it is that Duck duck go isn't a terribly accurate search engine compared to Google.

On my private PC I use firefox on my work laptop I use chrome. The gmail and gdrive integration just makes it easier.

Still on my private I have to switch to chrome for a few things because it just has more storage

Because the U.S. government used the 2001 Microsoft Internet Explorer Antitrust hearings to blackmail Microsoft into government servitude: implanting NSA backdoors, not patching vulnerabilities, disabling system administration tools, constantly hiding or moving useful features. Remember from the Snowden leaks that the NSA's favorite prey is the System and/or Network Administrator who holds all the keys? But what about the guy that makes the keys, wouldn't he be the biggest prey?