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.
I think there's an important distinction to be made between the different levels of earning to give. Really, there's a spectrum between "donate 5 percent of income" at one end, and "devote existence to resolving issue" at the other end. For humans trying to do the best they can, in fact, trying to scale up too fast can lead to severe burnout. So caring for yourself and having a good life and low stress is a good idea because it guards against burnout. It is better to donate a thousand dollars a month to resolve an issue than three thousand with an 80% chance of burnout. Slowly build up to higher points on the spectrum that don't give up quality of life.
Remember, the goal is to do that which works, not to win a "I'm way more hardcore about charity than you!" contest. If that which works leads to sacrifice and you can handle it without burnout risk, then sacrifice. If self-sacrifice doesn't work for solving the issue, then don't do it. And yes, aligning oneself with the people working on it and supplying them with resources is pretty much exactly what is required in many cases. Earning to give comes from the fact that the "supplying them with resources" step works much better with more resources, and working at high paying jobs is a good way to get resources.
And finally, about not understanding why someone would completely change their lifestyle to help as many as people as possible... Lifestyle changes tend to look really intimidating from the outside, not from the inside. In college, as an example, going "I'm taking >20 credits" makes people mightily impressed and worried about your inevitable lack of a social life, but once you actually start doing it, it doesn't feel extraordinary or hard from the inside. Dropping annual expenses from 60k to 15k is another thing that sounds intimidating, but from the inside, it isn't that difficult, and quality of life doesn't significantly change.
So that's one part of it, that it doesn't take as much of a sacrifice as you think. The second part of it is that if there is anything at all that you value more than the thing you would spend the money on instead, moving the money to the more highly valued thing is inevitable if you don't compartmentalize. I value ten lives more highly than purchasing a shiny new car, and I suspect that most people would agree with this. It's just a matter of acting on preexisting values and desires.
I am pretty sure "most people" value having a shiny new car more highly than the lives of ten unknowns somewhere far away. Revealed preferences are revealed.