I would imagine that there is caution about becoming beholden to user donations to continue operations. Such a situation would give users a measure of effective voting power in the development of the browser.
The C-level execs getting their salaries off that Google money can!
However with falling marketshare there comes a point that when that won't fool regulators anymore. And then there's no point for Google to keep paying.
Yes, better give it to Google and golden-parachuting C-level execs