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]
(..) Senator Paine to expel Senator Smith. Saunders must have the low-down on this. She packed up and left town. Paine accuses Smith of introducing a boys camp bill for his own profit! Paine's asked for a hearing before the Committee of Privileges and Elections. Frankly, my dear Senators, - (..)1939 Mr. Smith Goes to Washington
(..) the very land described in his bill. He bought it the day following his appointment to the Senate - - and is using his privileged office for his own personal profit! - Boy ranger had a racket. - This doesn't make sense. Accordingly, I offer a resolution for an immediate inquiry - (..)1939 Mr. Smith Goes to Washington