It's important to realize that Softbank's strategy may not be just to look at the startup's chances in isolation but looking at the whole portfolio of companies

It's important to realize that Softbank's strategy may not be just to look at the startup's chances in isolation but looking at the whole portfolio of companies in a space (self-driving vehicles) and look at a range of capabilities there. With their investments and their people on the boards of these companies, they can 'do more' to accelerate and make things happen which may not otherwise happen. So their view includes both the individual company, but also how it fits into the entire picture and that may give them an additional perspective and consequently a different notion of value than you or me as individual investors or analyzers would have.