If you are talking about bitcoin i will always hold. But if you are trading altcoins, i would always sell in a beginning bear market.
I made that mistake to listen to people the say "hodl" "hodl". I went in with 1k to get into cryptocurrency trading and lost almost 50 % because i was holding my altcoins to long. If i had traded them into bitcoins the my loss would be just 20 %.

I know the market is bad now and almost everyone lost money, but you loose a lot less when you trade your more unknown altcoins into bitcoin or eth when the market begins to "crash"
just my opinion