What about reciprocal cooperation with countries around the world? Foundation invests in country bonds, countries include small yearly payments (like dividends?) to the foundation.
There is more and more of these "essential global infrastructure" projects, many of them non-profit, yet I'm not sure we're seeing a lot of investment from the globe into those projects.
Dunno - it's worked ok for Oxford and Cambridge for many centuries, and the Church. I'd rather have land owned by vaguely public benefit bodies than some private equity fund.
What Wikipedia are you looking at? It's one of the things that has survived the longest on the Internet without being enshittified. It could live on in Cockroach Mode forever off the money from a modest solar farm or investment in an index fund. If someone sociopath bought the Wikimedia Foundation and tried to strip-mine Wikipedia, the Wikipedia editors could easily take a copy and go elsewhere.
Ironically, I was just listening to an interview with Jimmy Wales in which he said that, as individuals, most humans are basically good. They don't meet someone on the street and think "what is the rate of return on interacting with this thing?"
WHAT should the Wikimedia foundation invest in, that's viable for a thousand years?
That requires a Wall St/hedge fund and/or Buffett mindset.
The Wikimedia foundation is none of those, and they're not big enough to make even a ripple in the investment landscape.