story
Whereas the company maintaining the site as a whole has to invest a whole lot of time and money into keeping the site running, and have a huge responsibility in continuing to do so if they want to site to even stay in existence, let alone grow and succeed.
I don't owe Donald Knuth anything more than the $100 (placeholder) for his books, even if they helped me get a 6 figure job right out of college.
Yes, his books had a lot more "value" than $100, but those were the terms of the deal.
Stack Overflow wouldn't be a success without its users, but its users also wouldn't be a success without Stack Overflow.
Imagine, in some distant future, where users who contributed were also rewarded for their contributions when their community "gets sold". One of the comments above mentioned that their investment into the site is 0, that may be true for them, but I most definitely invested dozens of hours of my time in order to write a well informed and solid answers (as was demanded by their community guidelines, mind you).
I am not the best example either, I know people who have written thousands of high quality answers and god knows how many hours of their time into writing these.
My gut tells me that it would be fair, and make the world a better place, if such users were rewarded as well.
Also stickers and writing on the walls