I did a survey on Twitter asking where people bought their books from. 50% said Amazon and the rest was evenly divided between Waterstones and independent bookshops. None of my respondents said that they didn't buy books.
Whilst it does give a representation of people's book buying habits, with a sample of only 22 respondents it can't be taken as gospel. It is likely that no one claimed to not buy books because those in that category wouldn't answer the survey in the first place.
Love 'em or loathe 'em, Amazon is probably the future of publishing.