It happened to Lenovo and other laptops when they started installing spyware (Superfish) on their machines. They basically ruined the brand image that took years to build up.
They need money to achieve their mission though: maintaining a browser (in a landscape of evolving security challenges, performance & web standards) and research (e.g. projects like Rust, Servo & pdf.js originated that way) is not cheap. And currently it mostly comes from search engine deals. If they cannot get a similar one, it all collapses.
I can see why they try to diversify their income. That said, I don't agree with the way they do it here.
IMO coding missile software to pay for those projects would be a lot more ethical than what they're doing. Yeah I consider the ad industry and its privacy crushing consequences worse than weapons almost never fired.