Elon Musk's answers in 2007
Q5 Why go to Mars / what is SpaceX's mission?
The holy grail is helping make life multi-planetary. Mars is the only realistic other planet; even going from one planet to two is a big step. link
Q20 How hard should founders work?
SpaceX is the day job: about 80% of his time. He was chairman and principal owner of Tesla, not running it daily, about two to three days a month. link
Q29 How do you think about doing good?
For him it is always whether success would matter to the world; there are easier ways to make money than a rocket or car company. link