I wonder how much that is if you weight it by the bitcoin price at the time it was donated.
That's completely irrelevant.
Why do you think that? People have to pay their bills in fiat. So if you're working out what someone 'earned' from their work doesn't the exchange rate to USD matter?
I don't know but I imagine that back in 2011 Forrest made p2pool not for the money. But I think the world has changed since then. A lot of the modern miners spending $1,000s on new asics, the makers of those asics and the commercial pools attracting them are doing it primarily for the money.
Wish I had a solution.