Anyone who can find a spare $2k can buy one and quickly find they now have more than $2k spare, but you’d be amazed how many people, even in a rich part of the world like CA, don’t have as much spare cash as the average developer.
https://samvimesbootstheory.com/
Like I said, “not zero, but…”
You just need to count the number of rooftop solar installations there are in the world to get an idea of the market size. Another $2k investment to get significantly more value out of an existing multithousand outlay would be a no brainer for most of them.
Mainly I’m expecting grid-corrected batteries of this type to be owned and operated by power companies and governments rather than by individual home owners; and most privately owned batteries to be the ones in cars rather than permanently attached to houses.