I have no problems understanding this concept (it isn't all that intellectually challenging) but just disagree with it. This isn't a situation where if they make a bad decision it will do irreparable damage to the rest of their life.
It is one thing if monetary concerns were an issue. In that case then yes the parent has to step in. Other than that if your kid wants to try out for one of these teams is told of the 50% situation and still wants to play for them then you have to let them follow their own path imo. Again I am not sure how I would feel about it but I do know that I would let my kid make their own "mistake" if I gave them my (negative) opinion of the situation and they still wanted to do it.
Fair enough. I've let my kids explore paths that I might not have chosen myself. However, they continue where success is visible or at least possible, not where they're treated as an occasional role player while I sit back, watch, and pay for some expensive lesson in "adversity". It's one thing to allow a short-term mistake, and another to enable its continuation. I've seen my share of parents allow their kid's bad decisions to spiral out of control, leading to some costly consequences.