How can one type of coin wallet gain control over another unrelated wallet? Surely you would have cross site security of some sort?
The Lucky7Coin wallet story is kind of a red herring, the real hack was the Bitcoin and Litecoin wallets doing unauthorized transactions. Rouge code that allows the execution of arbitrary commands is nothing new, and should be planned for.
Why would Crypsty keep millions of dollars worth of coins online in hot wallets? Surely any exchange operator knows that's a no no.
Why would they know or care that it was a "no no." It's not their money that's going to disappear.
Oh I don't know, maybe because they're a fucking exchange whose bread and butter is in those wallets? I can't tell if yours is a serious question or just sarcasm. Perhaps you should use the [/s] or something similar.
This is either outright scam or severe mismanagement or gross incompetence. Time will tell.
Thier bread and butter wasn't in those wallet, their user bread and butter was in those wallets, they kept their bread and butter safe (or were able to keep going long enough after to make themselves safe, because I didn't hear any reports of staff going without salary to help make up the shortfall.
Doesn't really matter which of those 3 you listed it is, the end result for users in all those cases is the same, "sorry for your loss."