Is there any open sourced product that is actually main bread winner of the company developing it? Well Mozilla does it with Firefox still, but that is single customer just so that they can argue that they do not have monopoly and to drive traffic to their own product. But thinking of other examples. And I am here excluding those sold to someone else or are funded by other parts of business.
Netscape open sourced to try and head off Internet Explorer as a 'last throw of the dice'? Chrome based originally on WebKit from Safari which was forked off KHTML from KDE's konqueror, came along years later.
That's why open sourcing commercial products is silly and ALWAYS gonna bankrupt you!