> As the worlds richest man, dividing up your liability like that into many LLC's would seem like a very important thing to do

Unfortunately for Musk, when an LLC is used as a proxy for the single member without real separation, the LL part stops working as anything but (on a matter this size) a small additional speedbump rather than a shield, at the same time, it's even nominal separation makes it harder to make deals than if your hoards of assets were behind them.