Do you mean a random bonus of 15%? It will be not for all investors but only for one.
15% of casino profits will be distributed randomly between those who have more than 10,000 tokens. Well, it does not say that it will be only 1 person.
The profit of the casino may not be very high in the first year. Is the profit distribution determined by the team as a permanent bonus for the owners of this number of tokens? It depends on the stage when I buy 10 000 tokens?