Actually, I think the "scaling" is the money to hire the staff they'll need to improve their technology, in this time before they have a chance at a sufficient revenue stream to bootstrap.
Facebook-type users are a decade or more away from VR. They don't "do" fiddly interfaces and rough edges. Even if the hardware was there, the usability isn't.
And not unlike Facebook/Oculus, Google/Nest makes perfect sense from the Nest side and very little from the Google side.
In both cases there are potentially large payoffs in the long term. But they're extremely high price tags for decade-plus plays in which the acquired company has little to no particular proprietary technological edge.
Facebook-type users are a decade or more away from VR. They don't "do" fiddly interfaces and rough edges. Even if the hardware was there, the usability isn't.