For the fact that stock price falls by that significant percentage does not mean that is the beginning of the end of the entire industry. The going down of Facebook shares is not something that should be surprising to anyone in the know in the scheme of things. A lot of people have moved to other platforms where they get more fun couple with the data abuse controversy that happen sometimes ago.
The current downtrend is not expected to be permanent with the controversy wearing our gradually, the review of their advertisement policy on crypto, the rolling out of new features of videos, things would surely improve and more importantly, stock price is most importantly determined based on emotions of market participants.