I am not sure how reliable dicesites.com is, but I have used PrimeDice from 2013 onward, when they used to have a lot of promotional offers here in Bitcointalk. Also, they used to have one of the longest running signature campaigns here in BCT. The monthly maximum payment was somewhere around BTC2.40 (the exchange rates were lower then).
Even i am not sure about the reliability of dicesite but one thing i am certain is the site is one of the most profitable ones when it comes to online gambling dealing with bitcoin and with the price of bitcoin so high,it is possible to pull off those numbers as i am sure there are big whales rolling once in a while .I really miss those days when the price of bitcoin was below $500.