The demonym “Glaswegian” comes, linguists think, as an analogy of the Irish city of Galway. “Glasgow” and “Galway” are two fairly similar looking words. And Galway has long had its own analogy with another similar-looking word: Norway. Galway’s demonym is “Galwegian,” as an analogy of “Norwegian.” So “Glaswegian” is a sort of a photocopy-of-a-photocopy of Norwegian. Not something anyone could ever guess!
The fun thing about demonyms this is that there’s no grammatical rule for them.
It’s just kind of socially agreed upon.
Nobody from Boston would say they’re bostonite. They would say a Bostonian.
However, there are many more miltons. In the world around there are miltonians and miltonites.
People from Liverpool are liverpudlians.
People from Venice are venetian.
People from St Kitts are called kitty cats.
Meow
Another good one is Glasgow -> Glaswegians. Here’s a pretty interesting article about a few odd demonyms:
https://www.atlasobscura.com/articles/demonyms-linguistics-nicknames
And people from Wisconsin are called Cheese Heads.