the biggest regret that i can remember now is the day i know about bitcoin and ethereum, at that time, their price is so low that i can buy 3 or 4btc and hundred of eth, but i doubt these currencies and survive in the future and use money for another things, now look at their price make me so regret about that day.
wel this crypto world is the best regret-maker to anyone.
i was a holder of 500 eth back in the days ; and sold 'em at 8bucks