You should never sell all your bitcoin in any bull market. Sell some, keep some, it’s simple really. Always be prepared to buy some back in a bear market too.
in the bull market, of course, everything has to be sold, because that's a good moment,
if you wait for another bullishness and when you are bearish you are still holding the Bitcoin that you have bought at a high price,
obviously that's very unfortunate, it's better to sell at a high price and buy back when low prices occur, that's a good strategy.