I won't focus on this theory because it is NOT the real cause of hair loss. The problem is not sensitivity to DHT. Non balding scalps have normal levels of DHT. Only balding scalps have elevated DHT levels, mostly in the temporal regions and crown. And this DHT came as an and inflammatory response. When the inflammation is persistent and chronic it results in calcification and fibrosis and hair cannot grow. The galea of balding men is just not hair friendly. I suggest you to read the book ''Baldness a social history". Here is written that men who are bald have calcification of scull bones that blocks blood vessels. Bald men just lack that thick fat layer of skin under the scalp that helps blood supply to hair follicles. It is possible to create a baldness in a monkey by cutting slices of skin of their scalp and creating tight scalp. This fat layer this with the age and then baldness start. That's why some people who have healthy scalp with normal DHT levels when they are younger start to bald when they are older. This is normal part of aging and it happens in everyone. In some less in some more, in some sooner, in some later. But one is sure - this layer of skin is thickest at the center of the head and this area tend to bald the last if ever. I am starting to thing that the hair loss in older men stops to progress at certain point is because it is delayed due to lower DHT levels and if they start to take testosterone injection for example, they will end up completely bald. When they are younger the mechanical tension is not harming them because this fat is preserving their hair follicle, but when it thins with age the mechanical tension start very slowly damaging the scalp. And since this tension is highest at the temples and vertex, they are the first damaged. Especially the temples. They are very vulnerable. Then it is the crown and the center is the last.
The less of this of this layer you are born with, the earlier you will go bald. Why do you think that there are few Caucasian males in their 90's with full heads of hair?