[tlb]

It's a "good charity" because Bill is actively involved in deciding what are the highest-impact projects. Once Bill dies, it'll be managed by a succession of people who probably aren't as effective.

Also, the Gates foundation funds projects that create benefits that continue indefinitely, such as eradicating diseases. Better to do that now and have malaria-free populations contribute to their own increasing prosperity than to keep the money in a bank for later.