I would sell my Bitcoins if the price reaches to $ 5k. This is fair price range which neither is exaggerated nor undervalued like current price is. There are some predictions like Kim Dotcom said next year price will be $2k for a single Bitcoin. If that happens then $ 5K is inevitable. That is first target to see how price reaches there.
If the bitcoin price can reach $5k, it will probably reach $50k as well. So it is better not to sell.