Why collect payment in bitcoin and then pay winners in your token why not the same bitcoin and if I buy a lottery ticket from your platform can I play it in another lottery sites or the ticket is mean for only your platform because you state lotteries ticket in your post.
Afaik GUSD is not their token and it's reasonable to pay the winners with stablecoin since they're getting the same value and the prizes from irl lotteries are usually fiat. If the winner is desperate in having Bitcoin as a prize he/she could always exchange it and at one point he'll be forced to exchange those stablecoins anyway.