So Musk doesn't draw a salary from Tesla/SpaceX; he gets paid in shares. Since you can't eat shares (well, Pat probably can) Musk takes out loans against the value of those shares. Since it's a loan, and he has to pay it back, it's not counted as income; any more than when Fatrick buys something with a credit card it's not counted as income.
What Musk is counting on is those shares rising in value - he borrows a million on a million dollars worth of shares, and when it comes time to pay off the loan he sells them and hopefully the shares have gone up enough in value to cover the interest. That does mean that he needs to constantly increase the value of the company otherwise he's going to be on the hook for the interest; and so when things go to shit he has to
sleep at the factory trying to get everything working again.
The thing is, Fatrick could do the exact same thing - sign over the rights to his current and future works to a holding company, and then borrow money based on the value of shares in that holding company (I think David Bowie did something similar to this).
Unfortunately, Fatrick's works appear to be dogshit, and his further writings seem to make his existing work worth progressively less.