They can also use Yahoo or Bing as default for money.

The other option is diversify your revenue. Which is likely where the ad stuff comes in. If they can do that in a privacy respecting way with a facility to opt out, I have no objections. The loss of the biggest open source chromium alternative is massive and unthinkable.

For all the flaws of Mozilla, no one has forked, done better and put it out of business. It’s easier to run it behind a keyboard with zero responsibility.