I've also seen bucket shop used somewhat pejoratively when discussing crypto exchanges: not accusing them of never taking a position, but rather that they are u

I've also seen bucket shop used somewhat pejoratively when discussing crypto exchanges: not accusing them of never taking a position, but rather that they are under-collateralized or exposed to risk. An exchange, much like a ponzi scheme, could spend 10% of customer deposits and no one would notice until there is a 'run on the bank'. Similarly, they could choose to not execute orders to effectively take a position in the market - if the market moves in their direction gains can be huge, but if it moves against them it can be disastrous.