In this case you can only do one thing "Hold", this is the best option at the moment all the weak hands who sold their bitcoin will surely regret, another thing you can also do if you have a dollar you have to buy more bitcoin Every drop because this is a great opportunity that may not be repeated in the future. The market situation is now difficult and the global economy is in a downturn so it is better at this stage to leave work and go on vacation until the situation stabilizes. Personally, I am optimistic that Bitcoin will do it this time as it has always done and come back stronger than it was.
All those who collapsed when fear are surrounding the whole market those who sell their assets after the value went down to $17k they are all being played by the dumpers who quickly buy back the coin and pumped it back to $21K, it's always good to stay patient while the market is unsure, otherwise you will lose your investment.
There are lots of reason but if you are unsure better to stay calm and wait for the market to recover instead of trying to cut your losses.