Over 40s were obviously born before 1976.
That means many of them encompass the 60s and the rock generation.
Woodstock, The Who, The Stones, Carnaby Street, Summer of Love, and real socialist working class governments.
I am astounded that anyone can think it odd that someone from that era should continue to want to wear jeans as they progress through life.
My father in law wore jeans in his 70s, see loads of blokes that age in jeans.