I struggle with this. How do you know when to sell for good?
I suppose it is when you predict opinion is going to work against this and public opinion seems a very slow moving thing. Unless some sort of crazy event occurs.
The responses here are surprising. Your trading activity should be based on a strategy with a clear point when you should exit, e.g. you should have a prediction of how high an asset will go and sell when it reaches that point, or some timeline/portfolio risk mix that determines when you sell. And adjust that strategy based on new information (e.g. if you have a credible reason for why that strategy is no longer applicable you should adjust). Everything else is subject to bias and emotion, which is only useful at the casinos.
That is, you should NOT sell something because you're becoming emotional drained by it as someone else suggested. That implies you're not fit for managing and investing your own wealth. Don't jump off a rollercoaster while you're still riding it.
If you don't know what your strategy would be for bitcoin or some other asset, you should figure that out before trading.
If this kind of thing is longer term, you can play the "for free" game. If your 1 turns into 2, then sell the 1 (plus tax, etc) and you're left with your initial plus a freebie. Play with the ratio however you want, and repeat as you see fit.
One signal you can use for selling is if your investment starts giving you sleepless nights. If the value is going down and you constantly think about it then its better to sell instead of letting it affect you mentally.
I suppose it is when you predict opinion is going to work against this and public opinion seems a very slow moving thing. Unless some sort of crazy event occurs.