As
@stmarysmead illustrated, he is a young doctor.
The salary maybe great, but he can also have large debts. In addition to medical / dental school debts, he can have undergraduate debts (in an era when colleges are screaming for money, truly comprehensive academic scholarships can be extremely difficult to get- even for the gifted and hard working types).
In the end, I have a feeling that the true financial rewards of many doctors / dentists don't start until the debts are paid off and they have opened their own successful practices. This can involve business skills that not all of them may have.
As a result, buying a home in an area that can go from "pleasantly gentrifying" to "iffy" and back to gentrifying again by the block may not be that unusual.