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]
(..) It's more complicated than that. Macleish has got a duty to the client to get the best deal he can. Sure. But how many victims do you represent and profit from before you say something? Garabedian would say none. That's why he's taking these cases to court. He wants people to know about this. (..)2015 Spotlight