A big part of the reason browsers are so expensive to build and maintain is because Google keeps expanding the set of features browsers are expected to implement (and Mozilla offers no meaningful resistance to this.) Google creates a problem so large that only Google has the funds to solve it.
Right kind of attrition? Execs would fire every dev rather than themselves take a pay cut. The fact that this would actually kill the project is beyond them because they'd stay in office a little longer.