Yes, of course, initially. The risking it all period isn't when you're considering spending a few million to buy some rockets. But then the day comes when you're this close to finally succeeding, but you're running out of cash. You need more now to make payroll, and there's nowhere else left to get it. Sure, you could cut your losses and walk away with 3 million, but then a) you probably wouldn't have risked the 47M in the first place, and b) you likely wouldn't end up where Musk is now.

This isn't a hypothetical. As the article describes, there was a point when he was begging or borrowing every cent he could. I don't know what his personal financial situation would have been had it failed, but I doubt he held much back.