That is not entirely true, you need a coin that the price wont keep on dropping, so let say coin xyz is 10$ and you win ten coin xyz today, so your profit supposed to be 100$, but the next day the price drop down to 5$, so now your profit is 50$, you will want to avoid that coin for gambling, I personally like to used doge and ltc for gambling, the fee and the transaction speed is very fast, but the most convenient coin to used is still bitcoin because almost all of crypto gambling accept it