my life experience tells me that people dont change much after about the age of 25. By that age all your core beliefs are pretty much set in stone.
While that may be true for many people, it's certainly not true across the board. People who like to stay the same try to remain near their hometown and like long-term jobs, and try to avoid change. People who crave adventure and learning seek it out, with mixed results -- some good, some not so good.
Overall, if change were not possible, salvation would not be possible for the lost.