Investors are humans, like all the other humans, who happen to have the ability to commit significant funds to things, including startups, cars, and charities. There is a well- known challenge of putting large charitable donations effectively to work; that's why Warren Buffett put all his money into the Gates foundation rather than starting The Warren Buffett Foundation or donating it to the Red Cross.
Seen through that lens, it's straightforward to see how enabling people to come up with innovative and effective new charities that startup investors can help fund is a worthwhile project.
I didn't mean to say that they can't do whatever they want, or that they're incapable of helping the world. But if the investor does not expect his investment back, then that would make it a donation, which - as far as I can tell from the article - this is not.
"Since some people were confused when we funded Watsi, I'd better clarify that the money we're putting into the nonprofits will be a charitable donation, rather than an investment in the narrow sense. We won't have any financial interest in them."