> Even if they somehow imagine themselves as philanthropists or minimalists, they tend to put off giving away too much too soon under the rationale that they'll be able to eventually share more if they hold out and use it more practically.

What you're describing sounds exactly like Effective Altruism. The issue is that the expected value of an act that happens at an unspecified time in the future is zero.

> the expected value of an act that happens at an unspecified time in the future is zero

It doesn't have to be an unspecified time. Imagine you make $100K and want to donate $50K of that every year. One might say "well, I will bank that money instead, buy a property for $250K, then donate the rental income forever". You now have a specific time in the future (almost, depending on how property prices fluctuate in the next 5 years).