@gbryant Mozilla mainly works Firefox but not only but still has 1000+ employees and a 560 millions USD revenue.
https://en.wikipedia.org/wiki/Mozilla_Corporation
VLC core devs have a company where they sell service around VLC (integration, implementation of a new codec) which is profitable enough to give them time to work on VLC (I couldn't find a written source, don't hesitate to ask if you want more details)
LibreOffice: same as the kernel (couldn't find a better source) https://www.i-programmer.info/news/136-open-source/3716-libreoffice-development-status-report.html