forgive me if i am wrong, i don't know much about these matters. Just a quick thought. For me Elon Musks ventures seem a bit like angel-investors. Every company he founds has probability of making billions (car-company, rockets, tunnelling etc.), though they are also high risk. Of course he can't spread his risk as broad as a investor. But while risky, every venture seems to be very calculated, the opposite of crazy. I mean he could focus everything on Tesla, but if Tesla bites the dust he would loose everything.
But cause != correlation, maybe he just likes founding stuff.
But cause != correlation, maybe he just likes founding stuff.