Google's marketing budget for Chrome is greater than Mozilla's entire budget. They sponsor a Formula 1 team FFS. They spent a decade paying off Adobe, Java, AVG, Avast and all the other shitty free AV softwares to auto-install Chrome. They targeted Firefox users with Chrome ads on the homepages of Google and YouTube. That's literally billions of dollars worth of marketing alone that they don't even have to pay for.
Mozilla's competitors (Google, Microsoft, Apple) are collectively worth the GDP of three entire continents combined (Africa, South America, Australia) with a couple trillion USD to spare. Each controls an operating system (or two) with more than a billion users each on which their browsers are pre-installed.
No shit they struggle to compete on brand and marketshare. They're basically forced by the economics of the market to do search deals with Google, and whenever they try to develop independent sources of revenue people shit on them for that too. People shit on them for making deals with Google and make insinuations about them being "controlled opposition" because of that dependency, but also shit on them for pursuing any other independent sources of revenue, like the branded VPN service or the innocuous cross-promotion of that Disney movie with the Red Panda.
People shat on them for trying to compete with Android via FirefoxOS because the bet didn't work out, even though it was probably the only way they could have avoided this outcome and gained real independence, had it worked out.
"Just focus on Firefox", they say - unless that means laying off people that work on Rust, or AV1, or Opus, or WebAssembly, or Let's Encrypt, or experimental browser engines that wouldn't have been production-ready for a decade. According to HN, Mozilla should focus but also keep churning out and spinning off research projects, but only successful research projects, not ones that fail. Anything Mozilla does is always retroactively terrible if it fails but if it works out great they never get credit for it anyway.