Tesla isn't a car company. It's building Rome. All great "startups" are not some good idea executed well. They are companies with a long term vision that generate ideas to execute that will get them there. Anyone might steal an idea or copy a product, but no one can steal a mission or a destination far in the future. Apple, Microsoft, Facebook, Yahoo, Google... all started as or at some point became "build Rome" companies.
After reading this master plan yesterday, I came to work today thinking along the same lines.
I feel like Musk's actions are a great example of McLuhan's "The Medium is the Message". Tesla is not a car company. They're doing cars because it's a way into their actual business. He wants them to invest in solar power because it's another way that ties into a general plan.