I don't understand companies like this. Its founder is worth something like $5b, but instead of financing this venture with a tiny fraction of his net worth, Sh

I don't understand companies like this. Its founder is worth something like $5b, but instead of financing this venture with a tiny fraction of his net worth, Shaw decided to go get funding from several other firms. I understand the idea that a strategic partnership can add value, but having complete control of a company is also very valuable, and I don't know why Shaw wants to just give that away when it would cost him very little to not do it.