There was a similar story with Jason Trigg, an MIT graduate who went to work for a hedge fund just so he could give money away, also influenced by Peter Singer. See these discussions:

https://news.ycombinator.com/item?id=5800345

https://news.ycombinator.com/item?id=5819762

Here's the top comment from the second link:

Quote from quanticle:

If you choose a profession that doesn't arouse your everyday passion for
the sake of serving instead some abstract faraway good, you might end up as a
person who values the far over the near. You might become one of those people
who loves humanity in general but not the particular humans immediately
around. You might end up enlarging the faculties we use to perceive the far
-- rationality -- and eclipsing the faculties we use to interact with
those closest around -- affection, the capacity for vulnerability and
dependence. Instead of seeing yourself as one person deeply embedded in a
particular community, you may end up coolly looking across humanity as a
detached god.

Brooks sees this as a disdvantage, but I do not. Frankly, given the levels of irrational thought and behavior we see in the world today, we should be doing everything we can to increase the amount of rationality and far-oriented thinking in the world. I would posit that a world in which people were more like Jason Trigg would be a far better world, on every measurable metric, than the present that David Brooks endeavors to defend. I mean, Trigg, at least, has a goal and a plan to achieve it. The goal is the old utilitarian one of achieving the greatest good for the greatest number. The means is to earn lots of money and spend it on that goal.

Third, and most important, I would worry about turning yourself into a means
rather than an end. If you go to Wall Street mostly to make money for charity,
you may turn yourself into a machine for the redistribution of wealth. You may
turn yourself into a fiscal policy.

And what's wrong with that? The problem with fiscal policy is not the goal of fiscal policy. It is the coercive means used to achieve it. There is no coercion here. No one is forcing Jason Trigg to give away his wealth. He is doing it of his own volition. Were he older and richer, he'd be lauded as another Carnegie, or another Gates.

Making yourself is different than producing a product or an external outcome,
requiring different logic and different means. I'd think you would be more
likely to cultivate a deep soul if you put yourself in the middle of the
things that engaged you most seriously. If your profoundest interest is dying
children in Africa or Bangladesh, it's probably best to go to Africa or
Bangladesh, not to Wall Street.

That's not true at all. Sure, if you have skills that are needed in Africa or Bangladesh, it's best to go there. But not everyone has such skills. If we all pitched in like Jason Trigg and managed to get a cheap malaria vaccine crafted, say, 3 years from now, we'll have done far more good than if we'd all gone to Bangladesh or Africa volunteering to hand out bed nets. It comes down to the old question: are you worried about doing good or feeling good? If you're worried about doing good, you coldly analyze all the alternatives, and pick the one with the highest impact, even if it has zero visibility whatsoever. If you're worried about feeling good, you do what David Brooks advocates. You go down to Africa, Asia, or where-ever and get warm fuzzies by hoisting the white man's burden.

Rationality is not a sin. Calculation is not a sin. Money is not inherently sinful. All of these things are means, and have the capability to do both great good or great harm, depending on the end to which they're applied. Jason Trigg understands this. David Brooks does not. And that's why I, personally, respect Jason Trigg a lot more than David Brooks.