It is good that you are saying this, even if it sounds like a bitter truth, and most newbies must have fallen victim to this in a bid to think that they are being smart.

Rushing to sell below the price at which one bought his Bitcoin is dumb. Even from basic economics, when the selling price is less than the cost price, it is only foolish to sell at that price except you are dealing with a perishable asset that can't stay after a certain time. Is Bitcoin in that category? For Bitcoin, even letting it stay is the best way to remain in profit, which makes it dumb to think of selling too suddenly.

As opposed to selling when the price is below what you have initially bought bitcoin, it should be counted as an opportunity of adding more bitcoin and buying at a cheaper rate. Patience and discipline are what will help one make the best decision when the thought of making a dumb decision comes in.