Well I am day-trading alt and bitcoin, so I do not really have too much of a choice do I ? Well especially since I use automated trading and don't really wanna swap over to another marketplace so far; bittrex is doing a good job.
Then again I'd advise people to withdraw a part of daily earnings to a private wallet. I am also more afraid of people stealing my private data rather than the BTC I use for day-trading. Then again some people might stash way too many BTC in a marketplace