If I am given a chance to go back to 2020 I would hold my ETH very tight and never let go, when covid was hitting the world at its best I thought it over and I sold 24 ETH which I bought at 120$ each, I never knew I was so damn lucky to buy at that price, learn to hold tight if you believe in a project, there are countless of projects in past years that are way bigger in value right now.
It's okay mate what happens with you is a lesson. we regret sometimes but in then end we realize that regrets is very useful cause we learn how to do it next time. Like your experience you have a bog amount of ethereum but did not handle it properly and sell it when the price are too low.
Now you know for sure if you holding a coin you won't sell it when the price are low.