Ideally you should keep them, for now if selling is an unwise option. We can pray by 2022-2023 maybe these cryptocurrencies can grow back to the value it once peaked. The global economic market has not yet collapsed so we should not pray that crypto can grow steadily.
So those people lost their money for holding but then selling at the wrong time. If you once bought and you have decided to make long term investment then never sell your coins for panic. It will give you lose if you will sell it for being worried about temporarily falling price. We should keep our faith strong and keep holding until it fully recovers in the market.