AirBnB was recently valued at $1BN, so even if you assume AirBnB is worth zero, you only take a 25% haircut on this back of the napkin math (because AirBnB only represents $1BN of the $4.2BN in pg's portfolio). So, then you're talking about a lifetime 10X investor instead of a 13.4X investor. Still completely amazing performance, and he has a diverse portfolio of startups to protect him from individual blow-ups (such as assuming one of his most valuable companies is worth zero).