you can only withdraw when it is confirmed, but suppose:
I send 1 BTC to your site, with no fee.
I gamble it away, oh shit I lost.
Now I double spend the deposit, and I still have my bitcoin.
In case I won, I let it confirm and cash out afterwards.
It is still vulnerable.
@omahapoker, investing early brings no advantage.
You get a bigger cut, of a smaller pie.
When the site grows your cut reduces, but the overall profit increases.
Btw, there is a house edge, but that does not mean you will only see profit, so you should invest in a site with a lot of activity, than the variance is lower.
In that case yes, however we have some security protocols for it. our engine monitors deposits and link users together. we made it to prevent abuse on the faucet bot when we had it. We can block such users in future however we didn't have any such abuse in the past ( which doesn't mean we never see it ) but we are ready to it and will act accordingly.