I don't wear mine *that* low - they are saggy, but they don't fall down around the bottom of my butt
And I don't have to hold mine up all the time - sometimes I might need to hike it up once in a while, but it doesn't bother me
It started when I was working construction. My tool belt always made my pants sag and it just started to feel more comfortable to me. You know - the whole plumber's crack except my underwear hides anything that would otherwise be censored.
So I got used to baggy jeans with a slight sag on them from working construction.