[dimillian]

A bubble explosion would inevitably bankrupt the exchange platform first, then you. GDAX/Coinbase will never be able to create money out of thin air if everyone are selling and the BTC is dropping to $5. So even if you sell before everyone, even if you get your money on Coinbase virtually, they'll never honour the wire transfert.

[jfoldager]

Why will a bubble explosion bankrupt an exchange platform? The platform doesn't need to own any bitcoins and can be unaffected by price swings. The platform likely earns bitcoins through fees, but is free to trade them at any time. In principal all the bitcoins in the care of the exchange can be owned (or owed) to the traders.