I recall Nic "Star" Carter saying on podcast that the best historical predictor of a bitcoin bottom is that miners have sold all their coins. He was so resolute that it's the only bitcoin price signal I've remembered hearing (I also haven't bother to look it up). Perhaps the top is when they start selling after not having done so for awhile?

I emotionally prepare myself for the exchange rate with some thought like "bitcoin's price will go down by a lot in the short term, will go up by a lot in the long term, and possibly go to zero in the very long term." It's pretty indistinguishable from the common advice of "if you hold for more than four years you can expect gains regardless of when you buy." I just more explicitly expect to lose money.