But the parent to your response has a point - knowing that the answers are CC licensed and knowing that the owners might have a ten-figure exit are different things. If the community were more aware of the latter, they might have been more canny about donating their efforts.
I think they use CC BY-SA 4.0. There was some criticism when they moved from CC BY-SA 3.0 even when it was considered an improvement since it wasn't clear if stackoverflow needed additional consent to change the license for already existing content.
Of course, I never expected anything in return, but when you see that a small number of people get 1.8 Billion by essentially selling contributions from users, you start to wonder how much each accepted answer is worth :)
