When I talk to people about earning to give, it's common to hear worries about "backsliding". Yes, you say you're going to go make a lot of money and donate it, but once you're surrounded by rich coworkers spending heavily on cars, clothes, and nights out, will you follow through? Working at a greedy company in a selfishness-promoting culture you could easily become corrupted and lose initial values and motivation.
First off, this is a totally reasonable concern. People do change, and we are pulled towards thinking like the people around us. I see two main ways of working against this:
- Be public with your giving. Make visible commitments and then list your donations. This means that you can't slowly slip away from giving; either you publish updates saying you're not going to do what you said you would, or you just stop updating and your pages become stale. By making a public promise you've given friends permission to notice that you've stopped and ask "what changed?"
- Don't just surround yourself with coworkers. Keep in touch with friends and family. Spend some time with other people in the effective altruism movement. You could throw yourself entirely into your work, maximizing income while sending occasional substantial checks to GiveWell's top picks, but without some ongoing engagement with the community and the research this doesn't seem likely to last.
One implication of the "won't you drift away" objection, however, is often that if instead of going into earning to give you become an activist then you'll remain true to your values. I'm not so sure about this: many people who are really into activism and radical change in their 20s have become much less ambitious and idealistic by their 30s. You can call it "burning out" or "selling out" but decreasing idealism with age is very common. This doesn't mean people earning to give don't have to worry about losing their motivation—in fact it points the opposite way—but this isn't a danger unique to the "go work at something lucrative" approach. Trying honestly to do the most good possible is far from the default in our society, and wherever you are there's going to be pressure to do the easy thing, the normal thing, and stop putting so much effort into altruism.
"working at vampire squid headquarters..."
Earning to give doesn't require working for companies that are actively evil with secret malicious blow-the-whistle-on plans, and I don't think working for such organizations would be a good idea. But if you're working in tech (ex: me) or finance (ex: Jason Trigg) you can still fit in fine with your coworkers. You don't "ooze righteousness" or anything. (And I think trying to avoid coming off as "holier than thou" is very important if we don't want effective altruism to appear arrogant and offputting.)
"you can almost certainly do much more net good by going into engineering, medicine or similar and working very hard at perfecting something which has broad use"
You're making pretty strong claims ("outperform any plausible amount of giving") but the only evidence you're giving seems to be the claim that "in any given job, far more resources will pass through your hands than will be diverted into your bank account". Each individual doesn't have that much control over resources passing through their hands, while they have a lot of control over what they do with money they earn and can donate. But let's look at an example.
As the tech lead for the pagespeed module I'm one of ~10 people working on open source web server software that speeds up ~0.5% of internet page views by ~0.1s. There are about 1M page views per second on the internet, so every second we save people about 500s, or 500 person-years of time every year. That's 50-years per team member, so you could say through my work I save one life a year. Now for this work I get paid enough enough that I can donate about $100k/year. Donations to the AMF save a life for ~$2.5k but let's say $5k to be safe. So that's 20 lives. This is rough, but in my case at least my donations are going about 20x farther than my work. Add in replaceability and that shifts the balance even further in favor of donations.
I am reminded of an old Robin Hanson post on "helpful" professions.
http://www.overcomingbias.com/2006/12/do_helping_prof.html