if dicebitco.in works similar like just-dice I think your math is wrong, because there is a 10 % fee on investment profits.
(probably in order to pay for hosting, security and so on)
I forgot to mention commission, you're right.
Everything I wrote is true, BUT at the end of each week the site takes 10% of any new net investment profits from you.
As I understand it, DB works exactly the same as JD in that respect - if you lose one week and win it back the next week, you don't pay any commission on the part that recovered your losses, etc.
In BD there is no weekly commission.
They took 10% only when investor divests.
But yeah it is same thing I guess.