I never regret on selling my bitcoins as whatever bitcoins I gave that are earned and not invested so whenever I m satisfied with the price I sell my bitcoins as I know that I can earn it back.
Yes, after selling the bitcoin when price increases the mind agonize stating that we could have held it for a short instance too. This is quite the common feeling of human beings, but when we look at the thing for which we used the same amount, it gives us the joy and never lets us regret for the same.