What, specifically, should they have done differently that would have made Firefox not lose most of its market share to Chrome, and how do you know it would have worked?
Keep Firefox in focus instead of losing sight of the browser and getting distracted on a million side projects, most of which had only a tangential relationship to the internet. Raise money to support the browser rather than to support politically divisive causes of the month.
I can't say for sure it would have worked, but I know that what Mozilla actually did do was actively counterproductive.
I can't say for sure it would have worked, but I know that what Mozilla actually did do was actively counterproductive.