A lot of people change for good. Some people just fall off. Just trying to progress in anything, no matter what you're doing, I feel like any progression you make... some people aren't gonna be around you that were around you.
We are in a survival mentality, and that's hard-wired into our humanity, because we are the winners of an evolutionary struggle of millions and millions and millions of years.
It is characteristic of the military mentality that non-human factors ... are held essential, while the human being, his desires and thoughts-in short, the psychological factors-are considered as unimportant and secondary.