But there's also a 50% chance that he has to send 100 BTC out of his own pocket to another person, if they win.
Maybe a more extreme example will help you see the logical fallacy.
Say I have a BFL Single.
Say in a fair auction this will net 1000 BTC in tickets.
I buy 100,000 BTC in tickets from me. Cost = 0 BTC (moving BTC from one hand to another).
Chance I will win the BFL Single 99%.
99% of the time I will win my own Single and collect 1000 BTC in real tickets.
1% of the time someone else will win the Single and I still collect 1000 BTC in real tickets.
Ultimately using block chain can only ensure the drawing is fair. If the raffle operator is stuffing the ticket box you will still "lose" fair drawing or not.Note: nothing should be taken to indicate Matthew "stuffed" his own raffle just pointing out that there is no cost to the operator to do so. There really is no way to avoid such a situation. Even using something like OTC signatures only ensures the operator isn't buying tickets directly. He/she could still be using a proxy.
On edit: DUH. There is an obvious solution to ensure operator acts fairly. A fixed # of tickets. If the acution has a preset limit on # of tickets then there is no economic value in the operator "buying" tickets for himself.