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%.
Exchanges are also killin ETH by hiking the fees. They want to make times two of what miners make. They add miners fees to traders who are withdrawing. When you send from your wallet to exchanges the fees is not that much. Take a close look at withdrawal fees and you will understand what am saying here.