I think most traders often experience this, feeling sorry after making a sale because the coins they trade increase after he makes a sale. this can be considered reasonable in crypto trading because not only one or two people make a sale so that after making an automatic sale the trading volume increases
Not feeling sorry but feeling the regret of selling too soon.
This is normal to be honest since we are dealing with the most volatile investment in the internet or maybe in the world. The best thing to do here is to not stick with the losses you have but how will you be able to deal with those losses. Taking track of the losses you have, making strategies to be able to ready yourself in the future changes and holding yourself as an investor.
Many people likes to hold on to the past too much and we need to always understand that past is past, and there is absolutely nothing we can do to take back the hands on time, we can only learn from our mistake and hope it never happen again.
I am sure that now, the OP would have leaned and when he sees such opportunity again, he will know how to strategically manage it because sometimes, he could make that same decision and would be the best because market cannot be predicted and since we are not gurus to always know the movement of bitcoin, we cannot blame ourselves for it, we can only try, so we just need to be content also with what little we make from the point we sold, even if it became higher, at least profit is still better than losses.