How many times have you gotten behind some large sedan going 30 mph on the highway, only to notice it's being driven by someone born during the Great Depression? Do you stop to say, "One day, that'll be me!"
Because it will. Science is busy understanding why old people are the way they are, and they've come up explanations for things like...
Some elderly types have a kickass sense of fashion while others stopped buying clothes just after Lyndon Johnson left office. But regardless of fashion sense, most elderly men seem entirely unaware that their waists don't move up and down their torsos like some kind of wrinkled slide whistle. Thus they wind up with their belt somewhere around Superman logo height. Why?
As you get older, your body goes through changes even more awesome than the ones you experienced in puberty, which is to say everything puberty gave you falls the fuck apart. Muscle and organ tissue in your body may begin to atrophy and you can start to lose bone density as well. This in turn reshapes you into the Play-Dohy thing the grandkids want to exploit for money at every major holiday.
He used to be 6'7".
One of those changes sees your body fat increase by as much as 30 percent around your abdomen (imagine carrying around a large dog all the time, wrapped around your midsection like an amorphous cummerbund of waist obscuring crap). Suddenly the place you used to jack your pants up to is simply not there anymore and you can't tuck your shirt in quite right. So most elderly men go with the next best option and pull the pants up a little over that hump and do them up there.
At the same time that you're developing your brand new pant-suspending gut, your ass vanishes along with your hips. You lose all body definition that lends itself to pants resting at the waist, leaving you a stick figure of pale, liverspotty flesh.
Combine both of those with the fact you can lose up to three inches in height as you age, meaning your old pants drag on the floor unless you pull them up higher, and suddenly you have a trifecta of factors that will draw your belt to your nipples as if they contained electromagnets.