I think Doctors GUESS more than anything. Sometimes they are wrong and you can get even worse!!
Some doctors, like those who work for major 'Health Maintenance Organizations' here in he U.S., seem to obtain an amazing amount of compensation for 'guessing' in a certain direction. Inevitably that direction just so happens to result in huge spendings of their victim which ends up in the pockets of the pharmaceutical industry.
Note that if you are a 'very high net worth' individual, you A) don't need 'money' as most mortals understand the term, and B) have board seats on a variety of boards of directors in a variety of sectors. Or sub-sectors. If losses in one result in bigger gains in the other, that's fine.
I see most 'doctors' as being in the same class as most 'politicians'. They are almost all basically puppets. Some minority of them have some concept of how their strings get pulled, but most of those who do can find a justification to put on a set of blinders because life is relatively good for them.