All the giveaways, not only stakes but other casinos just share in the winner's list.
So, basically can be picked by them self without randomly picker. Unless they share some hash result from third parties are provided a random pick on their tweets, fun fact some giveaway on the forum (some of the moderator) picked their friend or someone they knew.
Giveaway like these, all you need to do just trust them (none fairness proof it's being shared). So, don't hope to much...........
This is why there are places in the world that does it based on blockchain or some other provably fair method. This would allow those places to make sure that they are not involved and they can't be called scammers or something. Like lets assume that you make a lottery game, and then everyone buys tickets, you sell a million dollars worth of tickets, then someone wins that million dollars.
The issue here, if it is not provably fair, how would you know if the person who won, isn't just some owners family member or something? That way they can keep the whole million dollars. This is why there is provably fair, you end up working towards making it provably fair and if you achieve it then people will trust you more, since they will be able to see if they won fair and square or not. This would also make people buy tickets a lot more as well but unfortunately that would require marketing as well, just trust alone isn't enough.
For you to have some decent return, you need to keep on having some personal effort towards making it known, trust is done by people who already know but if only a few people know it then it is not marketed very well. Like poker at stake, it is not marketed that well yet.
