The decline isn't due to costs imo. It has more to do with kids wanting to stay inside and play on their electronics. That decline is on all of us for not getting our kids into it.
Economists disagree with you. Increased cost always reduces demand.
There is a finite amount of discretionary income for everyone. A family outing to a dove field just got a lot more expensive. The heck with it, lets just rent a movie and stay home...............