Many plausible suggestions exist for a persistent decline of men wearing fedoras, but careful analysis with real evidence shows that they are false. Also, I draw a big distinction between internal and external causes. Internal causes lead fashions to change without any external societal changes. In many cases, commercial forces drive fashions, but even then their influence is still impacted by the internal change process going on. I develop a principle on the rate of fashion change.
Expensive products change in a slow way.
Cheap clothing permits fashions to change rapidly because new clothes are relatively inexpensive, and clothes are not terribly durable anyway. Fashions in furniture changes slower. Once consumers have something, they don't want to toss it out. They probably don't even look around if they are not in the market. Names are easy.