I'm quit trading too.... I depost 1 btc when it's 700$.. I make huge profit to 22 btc when it's 3000 and I lost 12 btc and sold 10btc when it 2k8$... now it 4k4... I'm feel very bad, very sad
I also have story...
I bougt bitcoin about 300$, and see etherium 3-5$. But didnt bought that period etherium nor bitcoin...
Not lucky

Or stupid )))))))
Dont be sad because you sell your bitcoin the price is low compared today because its your decision. So its better before make a decision think wisely and make a research first so you can know what is the best thing to do. I bought ethereum when the price is 10 dollars and I earn profit. The important you earn money in trading because other lose their money so you are lucky.
Yes, there is no use to regret now what had been done? You cant make changes to what you have done. But you can change your future by learning from your mistakes. Dont take anything on heart. Just stay calm and observe market deeply. Otherwise go for signature campaigns and make money without any tensions.