Never a bad idea to take your original investment off the table and keep the "play money" in play. You could reinvest the BTC and continue to bank more. Once your in the profit, you will be able to sleep easier at night.
I agree with you friend when I have 13 bitcoin first I want to do business and after I reinvest in bitcoin because when increase in price in bitcoin and after I sell bitcoin with good trader and take more profit and save money for future.