One interesting thing I saw in toy models is that a small number of incorruptible people (5% or less) can make it very dangerous to be corrupt. As corruption falls there's then a feedback spiral, because most people will report corruption if they're not corrupt themselves.
You definitely need a few people who are weird and unreasonable to start it off though. Have you seen the movie Serpico? I thought that gave a good portrayal of how odd and antisocial the people who cause that kind of change often are (and the real story was more so e.g. his marriage collapsed as part of the process). If we're going to be really speculative, maybe it takes an individualistic culture to even have that kind of personality?
You definitely need a few people who are weird and unreasonable to start it off though. Have you seen the movie Serpico? I thought that gave a good portrayal of how odd and antisocial the people who cause that kind of change often are (and the real story was more so e.g. his marriage collapsed as part of the process). If we're going to be really speculative, maybe it takes an individualistic culture to even have that kind of personality?