Probably boredom, though I'll also second the post that mentioned a life that has lost all meaning.
Another interesting poll question would be something along the lines of:
Have you ever read a post in PPR that has actually changed your views on anything?
I can't think of anything I've ever read that has, and I've never seen a post to the effect of "Wow, I used to think 'A' was the case, but now I'm definitely thinking 'B' is, all courtesy of what WP-member-whomever posted." And I won't be holding my breath awaiting reading such a post, either. But it would be interesting to see if such a thing has ever occurred, even if it is up there with unicorn sitings. 
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"The man who has fed the chicken every day throughout its life at last wrings its neck instead, showing that more refined views as to the uniformity of nature would have been useful to the chicken." ? Bertrand Russell