You can lose profit sending trading and withdrawing if you are trading a small amount I have $50 worth of Ferum or FRM it will take $6 to send the whole amount to Bilaxy and after you trade it to Eth and wants to withdraw it you will have to spend $12 to withdraw your Eth,
now that's $18 gas fees for your $50, my only option is to trade it to other altcoins like DGB or Litecoin which offer $4 to $5 fee you still going to lose $11, that's over 20%.
That's pretty common to happen. This is why most casual traders just leave their assets in an exchange, treating it as a wallet, to avoid losing in profit. Their taking the risk of losing their funds from hacks to avoid that fees. This spells disaster especially when the exchange you are trading with isn't very known. You can do that but it's really not recommended.