From Longman Dictionary of Contemporary Englishold habits/traditions/customs die hardold habits/traditions/customs die hardCHANGE/BECOME DIFFERENTused to say that it takes a long time to change to a new way of doing something → die
Examples from the Corpus
old habits/traditions/customs die hard• It was probably unnecessary, she thought, but old habits died hard.• Things were going well, but old habits die hard.• This is an area where old customs die hard.• But old habits die hard, and Apple has shown a proclivity to chase market share while hand-wringing over shrinking gross margins.• Perhaps because it's an island old customs die hard here. 