People do forget (I think deliberately) that London includes some of the most deprived areas in England, it's not all bankers rolling around in their money piles before going to race their supercars around Mayfair.
The majority of younger people, even in relatively affluent professions, in London will never be a position to buy a house unless there's a transfer of parental wealth involved. If you don't have rich parents, it's game over.