Is NYSE a scam? Is Euronext a scam? The exchange was a legit business that was profitable...outside of fixed costs, it isn't possible to lose money with an exchange. But they were doing other stuff (broking) that did lose them money. These are two completely distinct operations though (in real finance, they are largely distinct).
FTX, on the other hand, pretty much did just that.
Does that make FTX a scam? No. But when they told their customers they don't gamble with customer deposits, that was at least incomplete and misleading, and may have crossed the line into being intentionally deceptive.
Of course, even if people knew about this, they probably would have used FTX anyway because people do crazy things in a bubble market.
And whether they are gambling with your money or not, they were a mix of a bank and an exchange...so the comparison with a bank isn't complete. They were booking derivatives trades so your money is 100% at-risk, irregardless of what they do with customer deposits. This is what prime brokers do (as Levine says in that article).
The reason you don't lend against your own shares is because you won't be able to get financing and are exposed to runs. It is unrelated to the point about customers who were already at risk because they were trading derivatives issued by FTX.
It is, e.g., if the fees on the average transaction are lower than your variable costs. It is just extremely improbable for that to occur accidentally.
Only on HN.