> I can't think of any sport where players are expected to become coaches.

In amateur sports it's common. E.g. in rowing, cycling, fencing, cross country skiing, etc., people are generally expected to coach at some point. Albeit usually while they're doing the sport, and not necessarily as their primary careers.

Yeah, but this might be closer to "actors are expected to wait tables". It has more to do with paying the bills than career advancement.

To some extent, coaching something you practice is good for giving you another perspective on what it is you're practicing. In an ideal world, this will elevate your skill level.

This does, however, not necessarily mean that everyone is a good coach, nor does it mean that everyone should stop practicing what they're doing and focus solely on coaching.

Football/soccer? Of course there are more players than coaches so they can't all become coaches, but I would say star players are expected to become coaches, and lots of them do.

Oh, I agree, due to it being a pyramid only a fraction could ever become head coaches, so that wording was a stand in for that effect.