Fads come and go. And of course physical hobbies slice of the pie must be less due to video games...
Farming is being taken up by a narrowing population but I still see great attendance by the vintage tractor shows. Le Sueur Pioneer Power and Hastings Little Log House show are so crowded I might take a break from them. The steam school I attended in Iowa was practically standing room only.
About 10 years ago, there was a motorcycle chopper mania. Lots of people bought motorcycles and a gazillion chopper build off shows appeared on Discovery channel. Of course the fad has faded.
At least for me, I enjoy this hobby because of the mechanical nature of it. Although it's at least 50% computer based... Forums!