Incidentally, in case it's useful to anyone... The way I originally processed the $112M figure (or $68M as it then was), was something along the lines of:

• $68M pledged
• apply 90% cynicism
• that gives $6.8M
• that's still way too large a number to represent actual ROI from $170K worth of volunteer time
• how can I make this inconvenient number go away?

• aha! This is money that's expected to roll in over the next several decades. We really have no idea what the EA movement will turn into over that time, so should apply big future discounting when it comes to estimating our impact

  (note it looks like Will was more optimistic, applying 67% cynicism to get from $400 to $130)