Hi Hardy,
Interesting question. Are you looking for commercial support for a particular project? You can reach out with any of the companies listed here:
https://bigbluebutton.org/commercial-support/
As you may have figured out by now, BigBlueButton is an open source project for Web conferencing. Same as Moodle is for Content Managment for Education (LMS). The project itself doesn't make any money directly. Instead it is supported by the companies that are part of the ecosystem.
Responding to your question, as for any other Open Source project, free doesn't mean free as a free beer, but free as in freedom.
There are tons of resources out there that explain the business model for open source projects. You can start taking a look to this one:
Regards,
JF