The problem in my opinion is that we have reached peak advertising. Advertising is ultimately a doomed business model as it works against your users' interests, yet requires those users to willingly use the product and engage with the ads.

Over time, users learn to ignore it (see "banner blindness") so a short-term response is just to include more ads to compensate, but there's only so much space before the entire product becomes saturated with ads and users leave completely because the inconvenience of advertising became greater than the value the product provides. Regulators are also wisening up to it with stronger privacy protections (that threaten non-consensual ad-targeting) all around the world.

Advertising is a time bomb and an unsustainable business model. It provides short-term revenue (and a lot of it if you play your cards right, as Meta's stock price until now reflects) but will never be sustainable in the long run. Advertising is a parasite and its host will always try to get rid of it - a pretty terrible business model when you can instead align the incentives by charging your users money and provide them a valuable service in exchange.

Is there value in Facebook's products (whether current, or future VR-based ones)? Yes. Is there enough value to justify a overinflated stock price that only got there due to a combination of monopoly position as well as temporary gap in regulation against spyware? Doubt it, and so does the market.