I think I will hold. Over time, you will learn to recognize the periods in which to buy and which to sell. It is actually always depends on the currency that you are talking about. It also depends on your strategy. If you talk about btc, I suggest you to hold. One of the most important thing when we invest is target and stop. If you talk about eth, I suggest you to hold. For each trade we must set a clear target level for taking profit and more importantly, a stop-loss level for cutting losses, and you must decide to hold or sell according to it. If you talk about dash, zcash, monero, waves, and some other altcoins, I suggest you to ask some other people because I do not know, hahaha.