Very few make the research that you are talking about and sometimes when they do that all they think about is watch some youtube videos. That's how it happened with bitconnect. I am some kind part of them because almost every time I invested by instinct and that's not recommended. The problem was that I sold to soon. Patience is what I need. I will give you an example: at the beginning of December I bought some XRP and kept it for a week. After that I sold it because I saw the price was sitting between 20-22 cents while other cryptos where some kind of mooning. Not long after I sold it XRP mooned also so I learned to have patience. My guess is that in 5-10 years a lot of the altcoins would be history while the big ones would have made an entrance in the real life as real currencies used for usual purchases. For the moment my country is far away from this kind of situation so I am oriented more in earning profits from trading them that's why I choose the ones that are very often in the news. Even dogecoin has a chance of survive without the updates everyone waits. Simply because its community is strong and it has a lot of hodlers and support. Long story short I will follow your advice and do more of research about some cryptos since I am talking about them almost everyday.
Never regret if you have sold too early. If you made some profit, great, if you have sold at loss, learn from that and ask yourself why you have bought it if you can't hold when price drops. You can't change history and if you sold early, there must be some reason for that.