積重難返 [积－难－]

Jyutping zik1 cung5 naan4 faan2
Pinyin jī zhòng nán fǎn

Definitions (CC-CEDICT)
  1. ingrained habits are hard to overcome (idiom); bad old practices die hard
Definitions (Wiktionary)
  1. phrase, idiomatic
    established bad habits or practices are difficult to change or get rid of