This severe form of jealousy is primarily caused by the smaller city not having a stock exchange in their own town and causes them to “hate” the city that does.
E.g. Residents of Melbourne are envious of and therefore hate Sydney for its Prosperity, Natural Harbour, Major sporting events and concerts, Concentration of large corporate Head Quarters, Restaurants, The ability to great coffee anywhere as well as the ability of motorists to drive along a road without driving into pedestrians.
Their feelings of inadequacy are further amplified by Sydney not giving a crap about Melbourne.
Ask a Melbournite (especially if you ask a first Semester Uni Student who’s just completed their first Women’s Studies subject and has joined the Socialist Alliance or is a member of GetUp and voted for the Greens) what they think of Sydney and you will hear nothing but a tirade of abuse.
Ask a Sydney resident about Melbourne and they will say “Yeah, heard it’s nice there but I’ve never been” or “went there on business and had to laugh, they see three cars lined up at a red light and complain about the traffic”
This is also commonly known as the Melbourne Complex or the Vancouver Syndrome for their similarly unfounded hatred of Toronto.