Apple started their comeback with developers who liked the combination of a slick UI, commercial software and a unix shell (Got a G4 Cube around 2002 or so, then a Macbook). Dominating that niche made them hip and then everyone wanted one. The rest is history.
Everyone uses Linux, even if MS did everything to push MS on servers. And don't forget Apple spend millions (billions?) on pushing OSX to the server two (I had some XServe and XSans). But Linux dominated, and not because of Red Hat.
Many people and perhaps in the future everyone uses Postgres, even if MS and Oracle spend millions (billions?) to prevent this.
Brave currently tries to grow from the secure niche. I think Chrome started from the developer niche, with developer tools, being embeddable, open sourcing a rendering engine etc.
For a long time, chrome has had significantly better memory use. I really tried firefox again 2 or 3 years ago. If you have to keep jira open all day for work, it was unusable.
Regardless, your comment illustrates why Baker should have been fired for cause. Browsers are not really evaluated on technical merits past a minimal quality threshold. Rather, browser marketshare is built on distribution -- like any business.
And firefox was incompetent at that. Google has effectively used search; Microsoft effectively uses their OS; Apple effectively uses their OS, etc. And all products work this way: this is the reason Slack sold to Salesforce, ie Microsoft was using Office's distribution to effectively clobber Slack with Teams. The same reason that Google pays billions of dollars to Mozilla and Apple to be the default search engine.
What could have been done here? I dunno, but focusing on technical measures is not the right lens. BD is and was the necessary component, and that could have started with companies that don't want to see Chrome be the sole browser in the world. What could you have done to get eg Facebook or other companies with large web properties to ask their users to use Firefox? What partnership could have been forged with Microsoft when they were broadly uninterested in browsers? What could you have done to make Firefox a better browser for technical users specifically? etc.