Live by/on your wits - Idioms by The Free Dictionary
live by/on your wits
live by/on (one's) wits
To survive or make a living through one's intellect and resourcefulness. When I lost everything, I had to live by my wits, and it made me a stronger, more savvy person.
live by your wits earn money by clever and sometimes dishonest means, having no regular occupation.
live by/on your ˈwits earn money by clever or sometimes dishonest means: Patrick did not go to college, as expected, but learned to live very successfully on his wits.