Do you think that all of them never used a drug they are authorized to prescribe for their own personal use?
I do think that. The hospital where I used to work did a full pharmacy inventory of class II, III, and IV drugs every month, precisely for the purpose of finding inappropriate use of the drugs. In the inventories that I personally conducted, I never saw evidence that prescription drugs were used by anyone other than the patients to whom they were prescribed. I did hear one story of a nurse who diverted drugs to her own use (they were prescribed, but the patient never received them), and she lost her job and was probably prosecuted over it.
In the medical field, we take potential provider abuse of drugs very seriously.