https://public-001.gitsense.com/insights/github/repos?q=wind...
In the last 30 days, there were 2 frequent and 3 occasional contributors. I honestly thought frequent contributors would have been much higher, which leads me to believe the project is quite mature and they don't need a lot of people to work on netdata.
Based on Crunchbase, they've raised about 33 million so far and if the number of people required to maintain netbase is low (relatively speaking that is), I can see them not really needing to worry about making money and I'm guessing they are finding value in gathering data for ML.