Firefox is an ad company?

Okay, let's go with that premise, I'll rephrase.

So when options are

  1) Google, a $2.3T ad company
  2) Firefox, an ad company that Google pays $300m/yr for Google to be the default search engine
  3) Safari, a $3T ad company that Google pays $20bn/yr for Google to be the default search engine
  4) Opera, an ad company that Google pays ??/yr for Google to be the default search engine AND is Chromium based
  5) <other> browser, an ad company that Google pays ??/yr for Google to be the default search engine (and is likely Chromium based)

I am still failing to see the logic here. If anything, I'm more confused. What do you use? Ladybird? What about before that? Seriously, I'm so fucking lost here.