I'm a bit worried with the signature campaign. I have read in the September thread that the site spent about 12BTC that way last month (
https://bitcointalk.org/index.php?topic=758854.msg8625679#msg8625679). So, with a 0.1% edge for the casino (10% of the 1% edge), just to compensate that expense, 12 000 BTC have to be wagered per month. I wonder how much dicebitcoin expects to be wagered on the casino, but I think he's spending too much in that promotion.
What you have to keep in mind is that people invest and divest all the time, thus the owners make money even though the overall profit for the investors/site stays low/negative. E.g. the site is @ -50 proft and someone invests for the first time (or without prior negative profit). After a while the site grows to -20 profit, thus said someone has made a little profit depending on the amount invested. If this profit is divest 10% of it go directly towards the owners. IIRC it wasnt as high as 12 BTC for last month (maybe manl can give us an exact number?), but a new site is not expected to be profitable within the first few months.