I wouldn't be surprised if Zoom suddenly started exploiting browser zero days to force install things "for your own good"
Good thing that this is somewhat difficult to do ;)
Don't know bigbluebutton but at least among Jitsi and Google Meet, Wire is an alternative that is open source and end to end encrypted. They just don't make it easy to host your own, for that I guess Jitsi is the best way to go.
But how do they remain in business? I'm interested in knowing how say, Jitsi, earns money off of it.
Its wikipedia article describes its funding. It's basically a combination of sponsorships and paid employees working on it.