This post provides a lot of interesting thoughs but asks more questions than it gives answers.
Imho, $2,500 is way overrated.
But people will still vote, because of one aspect that @dantheman did mention: the gambling on posts.
If you see a post from a "usual suspect", in the 30min-1hour limit, it is a good "investment" to vote.
Not because the content is good, but because you are sure that others will vote.

For the record, I upvoted this post without reading it this morning.
Now i read it... and I read your comment too. That's the silver lining.

Again imho, "Upvote gambling" is part of the game, but it is for me the real cause of behaviors mentionned above.

@sebastien (just back from France !)