There are bugs in weekly ponzi to be sure. 1Excalibur took full advantage of one such bug or feature.
There was a 0fee TX one level above the deposit into WP and a later TX become confirmed, a feature in bitcoin where one can (re)spend coins if they are not yet confirmed. This nullified the chain, deleting it. This wasn't a slow process at all, it took 10s of hours.
At some time in the future the funds became available and WP started making payouts to any new deposits.
It's a matter of strategy, if you deposit the first day and then do nothing usually that's a win. However this time around it was a loss, one needed to keep depositing throughout the week. Even now is a good time to deposit, payouts after only ~7.25 BTC in under 4 days.
R u the OP

?
I'm not the OP, I just saw what was happening and read everything I could find about it. I intend to share what I know.