I would argue that electric car companies are appealing to a much smaller subset of potential customers than are self driving cars. But the mission behind each is very different and that flows into all the key design and marketing decisions you have to make.
Tesla can easily pivot from one to the other. But Musk is so passionate about the first, and therefore so are so many of their key people, that you wonder what happens if they pivot to being first to market with the best self driving cars that just happen to be electric.