First of all, a lot of these things are orthogonal. With that I mean, that they are independant from each other. The self-driving effort interacted only minimally with getting the Model 3 production up and running. As long as the money does not run out, it makes sense to do things in parallel, which are parallizeable. On the other side, Musk has a big picture in mind, which stretches quite a bit into the future. So these "side shows" actually fit together. You use solar cells to produce electricity, which you store in your power wall which can power your electric car.
If Musks ideas about self-driving actually become true, he holds the holy grail of the car industry. On one side, self-driving abilities become crucial in future car sales. On the other side, if he can make the Tesla car sharing network happen, the revenue of that could be a magnitude or more larger than the one of car selling. This would justify some of the crazier valuations of Tesla stock.
If Musks ideas about self-driving actually become true, he holds the holy grail of the car industry. On one side, self-driving abilities become crucial in future car sales. On the other side, if he can make the Tesla car sharing network happen, the revenue of that could be a magnitude or more larger than the one of car selling. This would justify some of the crazier valuations of Tesla stock.