This is more like a conservative investment in various things by the managing funds for 200 years, followed by a reckless investment in the cities of Philadelphia and Boston at the end of 200 years. It probably didn't do particularly more for the people 200 years from the time than it did for people in the interim.
Also, the most recent comment by cournot is interesting on the topic:
You may also be using the wrong deflators. If you use standard CPI or other price indices, it does seem to be a lot of money. But if you think about it in terms of relative wealth you get a different figure [and standard price adjustments aren't great for looking far back in the past]. I think a pound was about 5 dollars. So if we assume that 1000 pounds = 5000 nominal dollars and we use the Econ History's price deflators http://www.measuringworth.com/uscompare/ we find that this comes to over $2M if we use the unskilled wage and about $5M if we use nominal GDP. As a relative share of GDP, this figure would have been an enormous $380M or so. The latter is not an irrelevant calculation.
Given how wealthy someone had to be (relative to the poor in the 18th century) to fork over a thousand pounds in Franklin's time, he might have done more good with it then than you could do with 2 to 5 million bucks today.
That is unreasonable because we have more access to means of helping the poor today. If you expect the trend to go on into the future, than 2 million tomorrow is always better than a thousand today, which approximates maximal 3 lives on AMF of SCI
Robin Hanson wrote, five years ago:
In the comments some people gave counterarguments. For those in a rush, the best ones are Toby Ord's. But I didn't bite any of the counterarguments to the extent that it would be necessary to counter the 10^100. I have some trouble conceiving of what would beat a consistent argument a googol fold.
Things that changed my behavior significantly over the last few years have not been many, but I think I'm facing one of them. Understanding biological immortality was one, it meant 150 000 non-deaths per day. Understanding the posthuman potential was another. Then came the 10^52 potential lives lost in case of X-risk, or if you are conservative and think only biological stuff can have moral lives on it, 10^31. You can argue about which movie you'll watch, which teacher would be best to have, who should you marry. But (if consequentialist) you can't argue your way out of 10^31 or 10^52. You won't find a counteracting force that exactly matches, or really reduces the value of future stuff by
3 000 000 634 803 867 000 000 000 000 000 000 777 000 000 000 999 fold
Which is way less than 10^52
You may find a fundamental and qualitative counterargument "actually I'd rather future people didn't exist", but you won't find a quantitative one. Thus I spend a lot of time on X-risk related things.
Back to Robin's argument: so unless someone gives me a good argument against investing some money in the far future (and discovering some vague techniques of how to do it that will make it at least one in a millionth possibility) I'll set aside a block of money X, a block of time Y, and will invest in future people 12 thousand years from now. If you don't think you can beat 10^100, join me.
And if you are not in a rush, read this also, for a bright reflection on similar issues.