As a teacher and a basketball coach, I've observed a change in the attitude of athletes in the last 15 years or so. At the middle school level the number of athletes coming out for major sports, like football and basketball, has remained pretty constant. For example, I've seen as many as forty 7th grade boys come out for the basketball team. That number is quite large considering we are a small school with only about fifty boys per class. Since there is only one team, as many as 25 athletes get cut during try-outs. Of the remaining 15, everyone wants to be the next Michael Jordan or Steph Curry. By 9th grade, they've established a sort of pecking order based on their skill level, willingness to work hard, and individual development. If they can no longer realistically see themselves blossoming into a star, they leave the basketball program and begin to focus on the one or two sports where they have had the most success. This attrition continues until the 12th grade when there are only four to five athletes from the original 40 remaining. The varsity coach is forced to bring up underclassmen to put a team on the court. So we end up with a freshman, JV, and varsity team with about 10-12 players per team. Our high schools coaches seldom have to make any cuts, frequently taking players with no previous experience because the others have dropped out of the program to focus on something else.
The bottom line goes back to the unrealistic expectation that everyone is going to be the next star player. No one wants to be a substitute or bench player. They want to win and be part of a successful team, but not as a substitute. If I'm not a starter on the middle school basketball team, I'm done. If I'm not going to be the star on the team by high school, I'm done. If there is a younger player that's better than me, I'm done. Why waste my time with basketball when I can start on the football team, or the soccer team, or the track team, or the cross-country team, or the golf team, or the baseball team, or the wrestling team, or the bowling team, etc.