"About 80% of kernel contributors are paid – by their employer!" -- https://newsletter.pragmaticengineer.com/p/how-linux-is-buil... (from 2025)

Check out "Most active 5.10 employers" table (it's from 2020) on https://lwn.net/Articles/839772/

"Seventy-five percent of all kernel development is done by developers who are being paid for their work" -- https://www.linuxfoundation.org/press/press-release/the-linu... (from 2012)