As long as they are not greedy for profit, they can profit from bitcoin trading. The bitcoin market is still going up and down erratically and will continue to do so. People who already bought it at a low price can now sell it for profit but can also hold it for longer and only sell it when the price rises higher than it is now. Getting 20%-30% profit is enough because it is very difficult to make a profit nowadays.
The quick recovery is basically just the proof that we are in a market where 20k is pretty strong resistance. People know that it was the previous ATH in 2017 and they believe that we are not "that" bad right now and that is why buying when it is under there is pretty easy decision.
Doesn't mean that it can't go lower, it can still go lower way down if people end up selling a lot, but there is a difference between 40k and then suddenly under 20k, it is easier to buy some here. I didn't do it unfortunately, I should have done it, considered doing it but honestly I didn't had the courage this time around because felt like maybe it would go down more, it was a mistake, wish I bought some more.
Luckily I could buy a few bitcoins when they were under $20k. But I'm sad that I only bought a few bitcoins yesterday when I could have bought more. Maybe because I thought that my analysis had said the price could drop to a lower level but it turned out that the price could bounce after reaching a price level that I could buy. Well, at least I can increase my current bitcoin amount and what's exciting is that I can sell it right now if I want but I guess I'll just hold on to it for the time being. Maybe later, I'll sell some first, take my initial money, and save the rest for the next hike.