My biggest regret is when ICO lending (like bitconnect or hextra) was hype, and I was careless with investing my profits at the time. And I didn't sell some of the shitcoins I got from the bounty campaign, and now almost all the projects are dead and the tokens are worthless 
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.ICOs were extremely hyped back in the day ETH was just starting to blossom. As well as you did, I've lost the opportunity to sell some tokens earned from bounty campaigns when they were still traded on the market. If had sold all of my bounty earnings, I would've made a lot of money by now. Instead, I've decided to wait until prices became much higher on the market. It was a mistake by my end, as now I'm holding a bunch of worthless tokens that have been abandoned by their developers. It's up to this date, where I regret my actions taken within ICO's early days. At least, you get to learn from your mistakes.
I'd suggest that you quickly get in and out of new crypto projects to take advantage of them whenever it's still possible. If you plan on waiting for prices to become higher on the market, you might never get the chance to profit big time. I usually keep an eye on crypto projects to invest within their early days. Right after prices start rising, I quickly sell all of my holdings for profit. Repeat this cycle and you'll be successful in this wild journey of crypto. Remember, always do own your research and never make your decisions based on other's opinion to minimize losses as much as possible. Just my opinion
