Conventions satisfy a basic human urge: the longing for belonging.
At conventions, people who share similar interests - even obsessions - come together to bond and to be themselves.
The outside world doesn't matter. In fact, for the weekend duration of most conventions, the outside world doesn't even exist.
The conventioneers have each other and that's all they need.
The Mermaid Convention
The Ventriloquist Convention
BronyCon - The My Little Pony Convention
Real Bearded Santas Convention
Anthrocon - humanlike animal characters known as 'furries'
The Abraham Lincoln Convention
The Jehovah's Witness Convention
hat tips to http://coolhunting.com/tag/Conventional%20Wisdom and queensvillage1976 at https://www.reddit.com/r/exjw/comments/4zvzr9/spanish_assembly_at_bbt_center_on_lauderdale_14k
haha, I slipped that last one in
For more about the photo book see http://conventionalwisdom.com