I think it is a combination of a little of all those plus throw in a little bad parenting (directly and indirectly) it leads to kids leaving the sport.

I think we could all think of kids that left wrestling for each one of those reason you stated.

I also think there is no "fun" in wrestling. I don't mean that in a bad way, just look (what I assume is) at the majority of programs:

Practice 3 nights a week if not more, weigh in on Friday wrestle and travel most of Saturday. It is a sacrifice that we ask our kids to make. There isn't mush spending the night, going ot the movies, going to the mall, going skating. The schedule just doesn't allow it.

To help with that I encourage parent to schedule the tournaments they want to go to. Give the kids time off and let thme do these things. I had a rule for several years that I would go for 3 weeks them no matter what I was off for a week. It didn't hurt my boy in the long run. I also used to started tournament later than some did. Just things I did and everyone has their own take, but the main thing is control and moderation.

Kids still need to be Kids.