The problem with philosophy as a profession is that the product doesn't require very many competing producers. There are an endless number of problems that scientists need to solve. Why the sky is blue and why raspberries are red are very different questions. But Philosophy is largely a search of a Grand Unified Theory, and the number of people who we need to pay to think about the meaning of life is really quite small.
Not only are there few problems to solve, but the resulting product scales very nicely. Put a few geniuses to work on it and we can all read what they write. A handful of annotated anthologies of the great philosophers is pretty much all we need to get educated. We can't all go to the same few dentists, but we can all go to the same few authors.