first pay out is minimum worth $1
then when you reached $1, minimum $1.53
and so on and so forth, it will not let you withdraw your bitcoin haha! (it will show a popup that you have to invest $5 first)
The fact that the withdraw function went up is because it's in BTC and the BTC price went up, so that has nothing to do with the possible scam they are running... I invested 0.10BTC in it 11 days ago, and at this time I've been able to withdraw the whole 0.11BTC I "earned" up until now by withdrawing every 24hours, meaning I'm up 0.01BTC atm... Tomorrow it will be 0.02...
So ponzi or not, I got my money back in 10 days and everything I get from now on is extra. (I'm planning to reinvest earnings every 3 days, while withdrawing the other 2, so no more actual money of mine will go in, and even if it goes offline right now, I would have only gained from it.) Don't get me wrong, though, I don't wish it upon anyone to be at the end of a ponzi scheme, but at least I'm glad if it was a ponzi, I was high enough in the pyramid to have gained from it this time.
The site shows how much it has payed out to date, but it also shows the total bought hashpower thus far. If you calculate the cost of the bought hashpower, it ends somewhere over 1000BTC, but as we speak it has only paid out ~205BTC. As long as people keep buying with externally sent BTC, the site will have more BTC incoming than outgoing, but once that diminishes and the number of people just cashing out rises over the new-bloods, the paid-out amount will grow bigger than the paid amount for hashpower. Somewhere before that happens, the site will probably go offline and disappear... If it ever doesn't stop and continues to work after that time, the site has to be legit at least to some degree, though, since otherwise it's just handing out free money... Nobody does that...
You could still risk riding along with the ponzi and hoping you still are high enough in the pyramid to make it past the 10 days, but it's a risk none-the-less. The site could be there for weeks to come, but can also magically evaporate tomorrow... That choice isn't anything different from any other gamble, though, so it's up to you what you can miss and if you can risk it.
Anyway, I'm just glad my 10 days of stress are over and all that remains for me is just waiting for the ship to go down, only to see if it does or not... :p