This is a reference to Elon Musk's financial strategy, specifically https://www.reuters.com/article/us-tesla-offering-banks/elon...
Essentially, he has almost nothing in cash, and instead of selling stock to raise cash he borrows money with his stock as collateral. This is why he's so monomaniacally focused on his stock value and public image.
For a more professional, but login-walled, overview, see https://www.economist.com/business/2016/10/22/countdown