I agree, if you think you are in a profit after mining the coins, better sell it. We don't and will never know what will happen next. Better to book your profit and then mine the coin again. That way you are limiting your lost from sudden dumped and decline of price of the coin. don't get greedy and wait for 10x that is very rare to happen.
if mining bitcoin I think it is better to sell. because you have to pay monthly electricity. if holding also good if you have lots of money. because of course bitcoin could increase in the future. but not a good choice I think if you mine bitcoin and then hold it.
but if mining altcoin sometimes it is good to hold, because it has the potential to increase high.