Bitcoin is unstable, if you can not handle his ups and downs then you should not stay here.
Also you should make sure that you are not holding in bitcoins more then you can afford to lose, as bitcoin is not covered by any government and can be failed or lose his value and you may stay down without anything.
Selling at a profit is a good thing as long as you follow the those rules.
Bitcoin is always searching for a new value, thats what makes bitcoin soo unstable, as long you able to sell into profit i would make same way, but there is no way to predict what will happen with bitcoin.