[aDyslecticCrow]

You can always wait another year. And then another. When is it time? 50 years? 100 years? "We will maximise good by donating it all in 1000 years" is questionably not a charity at all; it's just a massive pile of money that isn't used for anyone but paying the people sitting on it.

Even if you trick-feed donations to charity over 100 years, the sums may be insufficient to reach a usable scale. - A big investment in research. - A concentrated push to vaccinate against a Disease so it goes away for good. - An infrastructure investment that lifts a community out of poverty.

These themselves produce "good over time," perhaps even faster than the money in the fund rises in value. It's a balance, but immortal trickle donations are likely quite far off to one direction of that scale.