You dont have to sell any really, theres no mistake just because a price changed.   Most of this decision is based on if you have to pay a bill or use those dollars for something, dont just hold plain cash because its being burnt up every day by government over spending; no regret is necessary really.  I didnt sell all at 60k I sold some in that rough area because I always have to sell some of what I buy, thats a normal trade.  Having a separate allocation to just hold is also reasonable, generally buying over time is best rather then specific prices to hold and same with selling roughly

The price in dollars isnt the way to determine timing or any success, I think one of the easiest ways to judge markets is the amount of hype going on.   Even within just this forum section, you could say well I have to sell something to pay a bill within this year and if every single thread is when does BTC land on the moon or giant hype titles then you far more likely to be in a time of over valuation.    
  If you sell now with constant gloom and no inflated expectations then you will get a bad price for the very same BTC that hasnt really changed.  Its never definite on the exact pricing but everyone can guess the mood of the market, a forced seller is somebody who has to pay a bill so write down all expected bills and thats your schedule of sale you have to meet ; now it just remains picking when the market is too hyped up and ignoring all the negatives in the world that can always happen.