professional thievery; thieving as a trade
Refers to theft as a regular occupation or way of life, not a one-time act. Often used in a critical or ironic tone.
He gave up his life of thievery.
Making a living by thievery is not something a decent person does.
泥棒 is a thief or the act of stealing, while 泥棒稼業 specifically refers to thievery as a profession or ongoing occupation.
Compound of 泥棒 (thief, stealing) and 稼業 (trade, occupation). The exact historical derivation is uncertain, but the meaning is transparent from its components.