Actually plenty of physical traits occur with no evolutionary benefit because the genes have been introduced to the gene pool but have not yet been eliminated from it
That takes a long time
And someone could have beneficial genes along with bad genes
So genes do not get completely eliminated like that
What is the evolutionary advantage of all the genetic disorders Ashkenazi Jews have
Based on your logic those genes would not exist if they did not have a advantage
What if the purpose of the baldness is to reduce reproduction rates of old men which provides a benefit to the community the old man is a part of even though it hurts the old man's ability to reproduce
Some bald old men are still able to reproduce by accumulating wealth
But the baldness reduces their reproduction rate
I am going to guess that the reason for baldness is that having less hair improves endurance exercise performance
It is claimed that humans do not have as much fur or hair as other animals because it results in better endurance exercise performance regarding sweating
The better question is why humans still have hair at all especially body hair