Mozilla (as of their 2013 financial report) had $250 million in net assets, and during the year received $306 million in 'royalties' and spent $295 million ($200mm on software development, $45mm on branding/marketing, and $30mm on general admin).
The Wikimedia Foundation (as of their 2014 financial report) had $54 million in net assets, and during the year received $50 million in donations/support and spent $46 million ($20mm on salaries, $20 mm on other, $5 mm on grants/awards. Only $3mm spent on hosting and service expenses).
There is no reason that these entities require that kind of cash flow, and need to spend that much money. Non-profit =/= money spent efficiently or effectively, and the people running these entities have managed to get themselves a very sweet deal by controlling what should in all rights be a community-led structure, and dipping their greedy snout in the stream of cash flow.
For those reasons alone, I refuse to support either of them. It is greed and control writ large.