Relax man, you earned money, that is enough, we ain't God or warren buffett.
Well yeah, people always tell me that, you can't think like that etc etc. The difference is, I knew that this coin would have success, and had it not been that I absolutely HAD to sell, I would never have sold under 10k... So, I will think like that, sadly.
If you feel that way, buy back in now. It's still very, very early. In the early days of Bitcoin, I sold my entire stake more than once and bought back in higher, because I wasn't ready for some of the more extreme volatility. At one point I was holding 3000 BTC. But everyone decides their own risk. I don't kick myself for not keeping that, because there were several points where it looked like it was about to be worth nothing. I don't think it was a mistake -- it easily could have become worthless at that point, and that wasn't a risk I wanted to take. So I didn't become a billionaire, but I still made a handy profit by keeping one ear on the rail and getting back in whenever I thought there was room to grow.
And how much more room is there to grow for Blackcoin (do you think)? 10x, 100x, 1000x growth?