My biggest regret is that when the price of etherum is around 100$ and I had not buy it. Because during that time I am not able to believe that the price of etherum will grow up soon. It is my bad luck that I did not buy it.
You can buy now massive amounts of Oyster Shell as it is trading for 0.15USD on Kucoin since yesterday and I think the vision of Shellis bigger and more disruptive than Oyster Pearl, I recommend to read more about it.
I sold some bitcoin when it was only $1200 and this is a bad thing for me. I was not patient, I couldn't hold my bitcoins. The result was very very bad for me. I missed thousands of dollars at the end.