If you are just going to do pure holding, you can earn big. But if you are going to hold and you can see that the price is already good for selling, then sell it and wait again for the time to become low, then buy. By doing this type of activity, your goal of earning big by not selling will become bigger as you are taking the advantage of it.
It's true, because if you don't have a target price when to sell, you'll miss a lot of chance of getting bigger profit with the market's buy and sell, pump and dump. When there's a pump just keep on waiting at a certain price and if you think that later or for the next days the price will be going down, just simply sell and buy at low.
If your earnings is only from bitcoin then you cannot afford to miss short term fluctuations as that is the only way from where you can make profits but if bitcoin is an investment or an secondary source of income then its better to hold them for a long term.
That is why don't always depend on bitcoin as the market is fluctuating and you can't have an assurance with the price to be stable, though it's profitable for us. Just like what others are saying, if you don't need money then just don't sell your bitcoins and just keep on holding so that when that day comes(high price), you'll be satisfied.