I think you’re massively downplaying how much of a hit this will be.

Let’s say you make $100k/year. Think about the lifestyle it allows. You’ve just been informed that it’s now going part time, and you’ll only be making $15k/year. How far does that get you?

Now, you’re expecting someone else to pay for that advertising spot, so it won’t be that bad. But who is even eligible? Microsoft’s Bing is the obvious answer, and probably DDG. The rest of the default search engines aren’t even general web searches.

Do you really think that either of them are going to pay any significant amount to be the default? Especially when most people are going to change it back to Google anyway, since these are automatically people willing to change to a different browser?

Sure, they might be willing to pay something. But it won’t be anything close to what they had before.

Flip it around - why would you work a job, any job, where you don’t know your pay until after the work is done?

“Tipping” is rich-people speak for shifting the expense (and blame) to the customer.