I think you overestimate the size of Mozilla Corp. As somebody mentioned above, the average CEO salary for a similar sized company is 800k.[1]
[1] https://chiefexecutive.net/ceo-and-senior-executive-compensa...
[1] https://chiefexecutive.net/ceo-and-senior-executive-compensa...
We were and are in the Bay Area, which is every year more expensive, but not 3x more.
It could be the 2.5m/year is justified, but not by market share up, new revenue lines, or both. What else? Competition? No, it is a custom fit job, chair of both boards and now even acting CEO. No competitive recruiting or chance for others to get the job, no real oversight.