Procrastination plays a part too.
It's a big effort to,
1.Find a good doctor (not all of them are equal)
2.Call to make an appointment
3.Take time off work/classes
4.Get there and wait, wait, wait
Really, all this could be solved if more medical school were allowed to be opened and get rid of the arbitrary ceiling on the number of students med school are allowed to accept .
This is only the easy part. If you don't have insurance, it's a nightmare.
In the case of my father, he went to a general doctor. Got referred to another specialist. Who then referred him to another specialist. $600 later (a huge amount of money to most normal people) and no diagnosis, he decided to just "deal with it".