If an admin wants to encourage those winners then should offer them some extra tips for posting proof on that thread then surely all the winners will post their winnings. All issues will have solutions just need to find them. Just offer small extra amount then everyone will rush to post their proofs.
FreeBitco.in does offer a reward/bonuse for posting proof of the big wins - as long as you have a screenshot. The OP to that thread (which is still very active) requests $200 and $20 winners to announce their good fortune. To be fair, it doesn't ask lottery winners to come forward, but lottery winners could if they wanted to.
Doesn't make sense that such vast number of people could settle to not celebrate their windfall. If one may ask, since when does winning a lottery became something to be shy of? I think the onus rests with Wetsuit to tell all of us here, we are bunch of unlucky folks, 
that is why no regular person here - Bitcointalk, have ever won.
that is why no regular person here - Bitcointalk, have ever won.I realize that this forum is a center of activity and discussion for anyone and anything bitcoin related. But that doesn't mean that everyone and everything bitcoin related is here. There's actually a very small community cruising these boards regularly.
If you broke down the math of how many members are actively on this forum out of how many people use bitcoin I suspect the % would be quite low.