The wider point here is that you can only use FF as long as Mozilla can fund it and Mozilla can only fund it as long as Google funds them. At some point, it will be cheaper for Google to pay monopoly fines than funding Mozilla.
There's penalties other than fines for abusive monopolies.
Fines are only the slightest punishment.
Fines aren't a way to just buy your way out of obeying the law. At some point if they persist in monopolistic activities then they will get broken up.