I was online when an attack was made on Etherdelta in 2017... In fact, I was even in the process of making a transaction to Etherdelta and do you know what saved my Private key from getting Phished?
Being phished means you visited a fake/cloned website . if nothing bad happens to you and you believe that you access the correct url of etherdelta then you dont need to question yourself on why you didnt got hacked .
Those users who used a Ledger Hardware wallet even in the time of the attack were safe since hackers can't access funds without physical access to the device itself. Another win for Hardware Wallets.
Hardware wallets are also exposed to attacks as soon as you already connect your hardware wallet into your gadget and your gadget is connecting online . those who didnt got hacked might not visited a fake website .