Scandinavians dye their hair black, brown, red, blue, pink, orange, and bleach it blonde. It's just for the fun of it and for a bit of change. There's no fascination with any particular hair colour.

I personally don't know anyone who is fascinated with dark hair.

There are many dark haired native Scandinavians and many immigrants from the middle east and asia with dark hair in Scandinavia.

Well if the norm was to have blond hair it wouldnt be that much fun. Some people like to stand out a little and others just like experienting. I dont think it has much to do about where they come from though.

they don't all dye their hair a lot of them have naturally black hair.

No