I used to work in a marketing agency, and had a few clients that heavily used advertising data.
I’d go as far as to say that while more data is nice, good data is much better. If Mozilla can somehow produce an advertising platform that is not intrusive, is opt-in, and has a wide enough reach to satisfy advertisers, they’re on to a winning strategy. Furthermore, they would need to codify any changes into Mozilla itself to ensure that advertising never gets to intrude on privacy or the browser experience - with the removal of the CEO and entire exec team as the cost for triggering this.
With all that said, I think the threat of doing this is probably a good thing. Mozilla’s track record of products is, frankly, piss poor. The thing is, everyone seems to be good at advertising, so there’s no reason why if Google leaves they can’t just say “fine, we’re an advertising company now” and eat their lunch.
It’s probably more on the lines of Google losing advertising share to every other company (Meta, Amazon, Unity, Microsoft) that has gotten into the ad business in recent years - all with minimal experience in ads, but either data, infrastructure, or visitors to sell. Mozilla definitely will have the infrastructure and visitors, even if opt-in.
I don’t agree that they’ll overtake Google, or could have overtaken Chrome with their product tie-ins/offerings. Google is a beast, whereas the average person probably couldn’t tell you who makes Firefox (or maybe even what Firefox is).