https://www.washingtonpost.com/news/answer-sheet/wp/2016/06/...
In this specific case, I am 100% positive that Mark Zuckerberg and Bill Gates are not investing in BIA to maximize their profit. They both have access to far more lucrative investment options.
I don't think this follows. You can't put all of your money into the most lucrative investment option. You have to diversify. For example people often invest in fine art, not because they're trying to make the world a better place by encouraging art, but as a hedge against other investments.
In this case there are assertions that BIA has a strategy of providing less individual attention to students in order to minimize costs, while taking money from the World Bank which could have gone to free public education otherwise. Sounds like Gates and Zuckerberg aren't in this to lose money.