People in power usually think that the best thing that can happen to the communities they govern is that they keep the power.
So they lie to keep the power, "for the good of the community". I think that they even believe that they are doing the right thing all the time :/
I've indeed observed this behavior, both in Free Software politics, and in "regular" politics.
I remember a specific line from the West Wing. Someone asks Toby why he's so focused on winning all the time. His answer: "We can't govern if we don't win."
Governing is an end in itself. Sad.