Well, if you are true trader then you should know that it matters. Fees can be a big impact on the earnings even if it is just small. Imagine, as you made transaction especially if it huge amount the fees will be high as well because it will be calculated based on the amount of your fund and there are times that the fees are almost comparable to the capital you invest. The fees from making a transaction and fees for withdrawal, if you combine them it could be fatal that is why traders tend to choose the exchanges that have low fees.