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.
You have to have the service mentality in the sense that you subjugate your own ego, and you subjugate a large part of your own life to really helping other people, being successful on their behalf.
If one advances confidently in the direction of his dream, and endeavors to live the life which he had imagines, he will meet with a success unexpected in common hours.