If you are holding Bitcoin from its all time high levels ($19k) to present day value ($4K) then I don't see why you should be selling. You have already taken a hit and the scope for downfall is very limited. The risk to reward ratio (For a believer in the future of Cryptocurrencies) at the moment is quite favourable for buying or holding. When it comes of having faith, absolutely. There are very few projects that I am bullish in the long term. Bitcoin, Ethereum (after upgardes) are definitely among those and we can hold them in the long term.