How Much Money Does VBulletin Make a Year?

Can anyone tell me how much money the owners of Vbulletin make a year.
Can anyone also direct me where I can find out how much other Vbulletin forums make per year.
Is there anyway to get an idea of how much these sites earn or is it up to each forum's owners whether they want to disclose how much they earn?
I can't find the answer anywhere else.
I think the owners of Vbulletin must be extremely rich and one of the very few success stories on the internet today.