That's what we expected, but actually today hundreds of people are doing it and sticking with it.

I think the key things that have changed include:

1. The existence of a community who earn to give, which makes this effect work in the opposite way. (You can also seek out firms with a good culture.)

2. People making public commitments of their intentions to donate e.g. through Giving What We Can, or Founder's Pledge if an entrepreneur, or simply telling their friends.