This actually makes a surprising amount of sense because Musk does not actually need to make Tesla eight times better of a company, he only has to convince the market that it is eight times better than it is now, and it will imagine that insane market capitalization into being.
Remember the wise quote of John Keynes: "The market can stay irrational longer than you can stay solvent."
Wow, I had not realized there were millions of litres of radioactive sludge that needed to be dealt with... but on the other hand, it sounds like they didn't either due to all of the secrecy.