Reputable exchanges don't keep trading assets they suspect are under 51% DDoS attacks. Coinbase shuts down assets at the slightest inclining of an attack. It pisses off their customers to no end, but guess what, nobody loses hundreds of thousands of dollars
This doesn't make them scammers
Yes it does....
They are selling an asset to someone and the buyer will never be able to take possession of said asset because the seller is refusing to deliver.
This would not be unlike if I were to sell a gold coin that I do not have and have no intention of delivering to any buyer (I would never do that).
That is actually very different since they have a market where you can speculate on the coin. If you were to sell a physical good that you wouldn't deliver that would be an actual scam since the buyer could never get anything back for it. Surprised this one goes over your head QS.
Any market can be used to speculate on the price of the asset. When you are buying a coin on an exchange, you are buying the actual coin, not a derivative.
If I were to sell a coin I did not have, and did not intend to deliver, the buyer could sell the rights to the coin to someone else if there is a willing buyer.
edit: How about this, you can send 0.15
BTC to 3P1o6BafmQomjKjakbK4ske8Lq8hCkJhiU to "speculate on the price of" 10 ETH -- I will not allow you to ever receive this ETH but you can sell this right to "speculate on the price" of ETH to anyone else who is a willing buyer. In my specific case, I am not scamming because I am disclosing your inability to receive ETH ahead of time, but LiveCoin did not do this, and as such is scamming.