Is it normal for guys to wear thigh-high socks?

That's the spirit!

My brother wears them he rides a motorcycle he folds them over top of his boots

My X used to wear high socks. I think maybe it prevent atatic on the pant legs.

If you have nice legs yeah it's normal. It makes no sense when people with chicken legs wear them.

Earlier it was normal to use with shorts, and it did protect the part beneath the knee.
Today the norm is shorts that reaches to below the knee.
Whatever the fashion is, the other will be "abnormal".

I mean, if you're into that kind of thing more power to you, but otherwise I'd say it's not normal outside of sports like football or american football.