A bank. A bank takes in at-call deposits and then loans funds out long term, for stuff like people buying houses. All their liabilities to depositors are covered by assets (loans), but if 50 % of customers suddenly withdrew their money, the bank wouldn't be able to provide it because they can't suddenly make their borrowers sell the houses they bought with the bank's money and pay it back. They would suffer a liquidity crisis, even if the bank is completely sound.
It's the same with pirate. Everyone withdrawing all at once and causing delays in pirate being able to pay out does not automatically mean he's running a Ponzi (although a Ponzi would show the same effect). It could could just be that his assets are not liquid enough.
The exact same holds true for any of the mining bonds and the like.