Implicit premise, that I haven't seen anyone point out:
It is assumed that while charity has a variable utility anywhere between 0 and X, selfish spending has a utility which is less than 0. This may be true in most cases, given that many people waste their money on disposable, consumerist garbage, but when considering somebody who spends frugally, their monetary utility will be in the positive sums (though arguably, less than any given charity).
He never said selfish spending has zero utility or less. He just implied it was less than charity. If you find a really good charity, it tends to be orders of magnitude better than keeping the money. For example, for $25 you could either see a couple of movies, or allow someone else to see the rest of their life. http://www.hollows.org/
There's nothing wrong with watching a movie. It's just not nearly as good as being able to see in general.
I'd be really interested to hear what the Less Wrong community thinks of this. Don't spoil it by reading the comments first.
.
.
.
.
.
.
.
.