[sathorn]

True, video chat is very expensive especially with the extreme bandwidth costs of the big cloud providers.

I built something similar as OP and chose a mesh solution for this reason even though it's inferior.

It appears that only big video chat companies like Zoom or Skype can afford to have a generous free tier, subsidized by their business offerings.

[dannyw]

They build their own DCs, and use cloud as a peak-smoother.

No one doing serious amounts of bandwidth pay outrageous big cloud prices. See: netflix.