[...] being mean makes you stupid.
Linus Torvalds is definitely not stupid, but I would not hesitate to call him mean [1]. But you can't deny that he's successful and certainly he's not stupid [2].Business and open source seem to both center around the same things: creating something people want [3] and surrounding yourself with other smart people. I would imagine that the latter is hard if you're mean - but not impossible. Take Linus or Steve Jobs, none of whom are very nice.
[1] https://www.youtube.com/watch?v=5PmHRSeA2c8#t=883
[2] http://www.wincent.com/a/about/wincent/weblog/archives/2007/...