Do you think I can get away with using a single speed bicycle in Chicago?

I know a lot of folks who use single speed bikes. The city is mostly flat, so you hardly ever need to change gears. I talked a while back to a guy about what bike I should buy (he worked at a bike shop), and he told me a lot of people had to have their bikes fixed because a single gear was all worn out. People don't switch gears very often and wear one out while hardly ever using the others.