Why are some Londoners so aggressive/protective when it comes to the 'pace of city life', and why is there this concept that city life has to be 'fast 'n' dangerous'?

Was just closing my anti-cyclists-who-jump-red-lights book on Facebook when I saw a response from some meathead to my (admittedly similarly aggressive) ranting, and it went something along the lines of

'u dont like the pace of london life so why do u live here u prick? get the fuck out of my city. if i see you i will run you over and stab your brains out wiv my bike chain'.

Actually, London isn't such a fast place. I live about half a mile from Epping Forest and it's quite possible to sit there and spend a dozy afternoon by the lake. The only concession to 'city life' is the ice-cream store that insists on playing house music.

'u dont like ice-cream men playin house music? get the fuck out of my city. u cant stand the pace. if i see you i will slash ur face wit a broken CD' etc. etc. etc. ad infinitum.

Baffling.