... in World of Warcraft.
I have seen some people change in my lifetime. Usually confronted with some huge issue such as a chronic health problems, or a change in where they live, and sometimes I have seen people change for no reason other than they wanted to. But, in my time playing World of Warcraft, I have not seen someone change how they acted towards other people.
Most of the time, people put on a front. A fake outward impression of changing, but underneath, they are the same. I have seen guild members in my guild who stopped doing something when people said they were being annoying. The behavior always came back. I have confronted people about breaking rules, and they broke them again. Often times trying even harder to justify why they did it.
Currently I feel that if someone were to make a change in their life with respect to World of Warcraft, their first change would be to leave the guild or quit playing before altering their behavior. People don't change because a disembodied voice or some text in a video game tells them to.