The SoftBank Vision Fund’s self-driving car deal with General Motors is more than a way to hedge its many bets. The huge Japanese investment outfit will sink $2.25 billion into the U.S. carmaker’s autonomous-vehicle unit. The risk may not be spreading its holdings too widely, but doing it too early. The Vision fund has certainly been spraying its nearly $100 billion of cash around. Earlier this year, it took a 15 percent stake in ride-hailing firm Uber, which is also developing self-driving vehicles. An investment in chip firm Nvidia is also a play on AV technology, as that company is