Having bought Litecoin at 10 EUR at the end of 2013 or beginning of 2014, holding during the Huobi/BTCChina (can't remember) pump to 16 EUR and watching it plumet to 3-4 EUR. Stayed there for three years, but I kept holding. Noticed there are always fluctuations between 3,5 and 4 EUR. Decided after three years of bagholding to recover my loss by swingtrading on those fluctuations, so sold at 4 EUR one evening and put a limit buy at 3,5........... which never hit because that evening I sold was the evening before the BIG SEGWIT PUMP TO 35 EUR.
That happened to me because I didn't really follow cryptonews a few months ago, was out of the loop and a complete beginner. Learned a lot in just a few months and now I keep up with news and follow other people on Twitter (and realized how little I knew about crypto, a lot has changed since 2013-2014 when I was in the loop).
Plot twist: What makes this story from ultimate bad luck to a huge success story... a little later the Ripple pump started and also the ETC pump. I figured, hey I should just buy a random coin and see what happens. So I put the fiat I got from selling my LTC at a huge loss in... Stellar Lumen! And just one day later it started pumping x20. My profits were massively higher than if I were to stay in LTC and magically called the top to sell.