I agree that the link is probably heavily sublinear. But I wonder if it becomes less sublinear if one is more conscious of impact-per-dollar.
I’ve had this experience myself, sort of, in that I began to enjoy giving more after I found EA and my previous “well, I hope this works” feeling resolved into “yes, I found the best deal on helping!”. And since I know that I’ve found a good deal with high-EV returns, giving more does feel better, just as it would if I were depositing more money into a high-yield investment. Meanwhile, because I have enough money to be materially comfortable, the idea of “$1000 in savings lets me skip working for another two weeks in 40 years, assuming I even want to stop working” doesn’t hold much appeal, compared to “spending $1000 on one of the world’s best products”.
I think there are many other use-cases for savings than just retiring earlier (e.g. Jeff & Julia’s mercury catastrophe, which cost $50,000 to clean up).
This is certainly true! Money can buy almost anything, including security against future disasters. I’m only making a personal claim about myself and my own use of money. I personally often feel like giving is the form of spending that will make me “happiest”, because it feels like a direct path to me getting a sense of personal satisfaction in a way that saving often doesn’t.