Someone probably should never keep their extra coins in a exchange, if someone feel that they don't want to pay the fees of deposits everyday as they do trading everyday then they should just keep their capital in the exchange and take out the remaining btcs from there as it really can be dangerous.
But then people are hard headed and never learn, me included lol. It had been a hassle withdrawing and depositing Bitcoin when trading, especially you have a buy order to be filled. You cannot withdraw the bitcoin placed in a buy order because you need to cancel the order in order to withdraw that Bitcoin.
I have a question about this: If any exchange get "hacked" (Wether it's an inside job or no) the Bitcoin price will go down like the Mt Gox case or Bitfinex in august, so what do the hackers do with the stolen BTC? Hold? Spend? Dump?
Depends on the hacker really. If I were him I'd slowly sell it, so that the bitcoin price doesn't get affected that much and the exchange which I'd dump it on doesn't get suspicious.
Indeed hackers need to sell the stolen bitcoin slowly, even if it is free, their aim is to get a high rate as possible. So most probably they put the lowest sell wall at least higher than the buy wall and put it in chunks.