For me it is simple: Capitalism searching for the next virgin real estate to "capitalize" on.
First mover advantage appetite is pushing Facebook to double down on it despite the obvious fact that the tech is not ready yet.
IMO it is going the be the 10th next big thing, maybe in 30-40 years, when we will have optical computers able to process real-life-like virtual environment auto-generated by advanced AI models (and maybe fusion reactors to power them, one can dream)
What is the rush? I see Zero benefits for humanity. It is all just bling.