noun
predatory nature; rapacious disposition
Refers to a greedy, exploitative character, like that of an unscrupulous palanquin bearer (雲助) who would overcharge or take advantage of travelers. Often used in critical or moralistic contexts.
あの商人の雲助根性には呆れる。
I'm disgusted by that merchant's predatory nature.
彼は雲助根性をむき出しにして、弱い者から金を巻き上げた。
He showed his rapacious disposition and extorted money from the weak.
雲助 originally referred to a palanquin bearer, but later took on the meaning of a swindler or exploiter. 雲助根性 is the disposition or nature associated with such a person.
根性 means 'disposition' or 'spirit', often with a negative connotation when combined with a negative prefix. 雲助根性 specifically denotes a predatory, greedy nature.
Compound of 雲助 (palanquin bearer, later associated with swindlers) and 根性 (disposition). The term 雲助 itself may derive from the wandering, cloud-like nature of such bearers, but the exact origin is uncertain.