"Should I sell or hold?" - perhaps this is the biggest problem for all holders at this moment, when the expected return has been met, but everyone want to continue to keep and receive greater profits in the future. I am holding ETH, even if it is only a small asset, it makes me feel insecure every ETH price below $1K 
I believe that the impact from Halving and ETH2.0 will continue to provide momentum for the crypto market in 2021 similar to 2017. So I decided to sell by the end of 2021.
There has probably never been a similar situation on the cryptocurrency market. On the one hand, Bitcoin recently crossed its previous price record of $ 20,000 and is already at $ 35,000. Despite the optimistic forecasts of its growth, few really thought that it would reach its current heights so quickly. Previous experience suggests that such a high growth should be followed by an equally deep decline. However, the situation is now special. Instead of a logical fall, Bitcoin may well grow in price further.
Altcoins have slightly increased in price, but their season is expected after bitcoin reaches a price peak.
Therefore, now everyone should do at their own discretion, depending on how confident they are in the further continuation of the price growth of our cryptocurrencies.
I've sold my cryptocurrencies a little now and keep them in USDT in case the market falls, but in general I expect it to rise.