He 'profited by' his experience/mistake. [=he learned something useful from his experience/mistake]
The book can be read with 'profit' by anyone who wants to understand how the system works.
We sold the house 'at a profit'. [=we made a profit when we sold our house]
(..) - But that hasn't stopped... - That's never been proven. Yes, it has. The Lutz family made everything up so they could profit off of all the publicity. That's just not true. Look, we see this all the time. It's very easy to sit on the outside and pick apart their story. (..)2016 The Conjuring 2