Of course, there are edge cases. Some assets will keep climbing for a very long time, others will go to zero. But that's where diversification and value analysis (should) come into play, not succumbing to human psychology.

Make sure you really understand this and don't fall for the trap of "omg why didn't I sell" if we go down further after the fact. The (mathematically) most sensible thing to do is to keep buying in small batches and decide on different price targets at which you will sell. This includes higher prices at which you take some partial profits, as well as a full stop at which you get out of the game entirely. I'm personally riding down to zero if I have to, but for others it might be more sensible to scrape.

Just be aware of how markets function and decide on your strategy before you get into the game, and then take whatever you get without beating up yourself over it. Invest that energy in learning how to do better next time instead of FUDding/FOMOing out/in.