" The majority of Mozilla Corporation’s revenue is from royalties earned through Firefox web browser search partnerships and distribution deals around the world. Mozilla Corporation’s revenue and income support for CY 2016 was $506M, as compared to $414M in CY 2015. "
Let's assume that "browser search partnerships" is what google/yahoo paid for having their search engine be the default in the search bar - "distribution deals" sounds just the sort of thing this thread is concerned with.
So: half a billion figure - check, shady consideration for the money - check until proven otherwise. FUD you.
I don't think that actually is correct. The Mozilla Foundation is a non-profit, as has already been pointed out above. As such, they specify a mission and then are legally forced to invest all money that they make/get into this mission.
And in their mission statement, they specify that "Individuals’ security and privacy on the Internet are fundamental and must not be treated as optional." (Principle 4 in the Manifesto).
So, they cannot legally do shady stuff. And even if that means nothing else to you, the rule with law violations still is "Innocent until proven otherwise".