Your casino only have single game e.g. dice, I'm not sure how this can attract many gamblers to play in your casino because there are plenty of casinos already have dice and also other games too. You're not completely too by saying many dice casinos has 3-4% house edge because I see there's many casinos who have 1% house edge too. It doesn't make sense a simple game e.g. dice charge a high house edge, obviously many gamblers will not play anymore.
if nothing else, they manage to get their curacao gaming license here even if we say they only have dice. because most newcomers with only 1 game, they don't bother to get licensed upon introduction to the public. they can expand their games later on adding more classic games. remember other dedicated dice sites before has only dice and then later on, they added other casino classics, even adding sportsbooks.
but checking their jackpot - they are already raking big here considering that they are relatively new. so maybe this site has been promoted outside the forum before they created their thread here. as the stats are also quite large for very new dice site, just look at their amount paid in $.