It's pointless to even try and calculate this number. There are ~3000 billionaires in the world. Most/all of them have children, and I'd wager a large chunk of

It's pointless to even try and calculate this number. There are ~3000 billionaires in the world. Most/all of them have children, and I'd wager a large chunk of these children have access to >$1B of the wealth, whether on paper or not. The only special thing about these 15 is that their parents are dead and/or their inheritance or trust fund has already kicked in.