I got into Cardano some months ago but we know that before the bullish state it is now it was not moving that much which was really a big boredom for many. That boredom got into me and a month ago I let ADA go for Ethereum. Well, right now, the moment of regret came when ADA made many jumps in price.
Haha I did exactly the same thing recently. I was trading ADA/ETH and had already taken some profits a few months ago and recently it seemed like it was breaking down so I reduced my position at break-even. At least it went towards NFTs that are doing better than Ethereum, but definitely wish I had patiently waited in order to take more profit now as originally planned! For me this is a lesson is "sticking to original plan". It was supposed to be a mid-term profit hold for the year, so I was cashing out much earlier than planned.
Have you experienced that kind of feeling when you see the coin you let go is now moving up the ladder? This happened to me a lot of times and I even concluded that I must not be a good crypto investor as I let my emotion get into me.
I avoid ever fully letting go of an altcoin, I take 50% at 2x satoshi profits in order to only be invested with profit. Then another 50% at 4x in order to double my Bitcoin holding. Then I usually let the rest ride (25% of position) until I see it breaking down or otherwise overextended, then I sell another half and so on.
For sure there were times like with Matic where I had already taken 75% out for profit, and had I held it all I would have made 4x more satoshis in the long-run, but ultimately it doesn't bother me anymore. I never have these regrets, 95% of the time the right thing to do is to sell half at 2x, and continue taking profits, as it's too high risk not to.
That said, I have over 50 shitcoins so it's a bit different than picking a handful of gems and getting emotionally attached. I just do it for satoshi profit...