They vanished from 'in'. From the moment the moving picture was invented, all the men were in hats. All the way through the 40s and 50s, all that newsreel footage- endless hats.
Then suddenly, in the 60s... NO MORE HATS!
I hate that. I want to wear a nice trilby. But no, go out in a hat these days and you get knifed.
Probably the greatest tragedy in my life, except for the lack of lesbians making out in my room.