Holding is very risky because you didn't know if the price of the coin you hold will return to it's ATH so, be smart and always take the risk. I think it's better if you hold the 50% and sell the another 50% to save even a little if your holding turn to lose.
I agree, hodling atleast 50% of what you have and sell the other half. You'll never know when will its' ATH will reach those numbers again, and as expected, in few more weeks, bitcoin's value may surpass the ATH of 2017. Lets all hope for the best! Lets hodl up to Q1 of 2021.