In my experience, most bookstore staff read pretty heavily.

I used to spend a lot of time at The Center for Science Fiction Studies at the University of Kansas, and got to meet a lot of scifi and fantasy writers. The topic of whether hard SF was the only true SF came up a lot, and pretty notably almost all of them derided the notion- especially the hard science fiction writers. (At minimum, because soft scifi is a bit of a gateway drug for hard scifi- not a lot of people jump straight in the deep end.)

All that being said, I do love me some hard science fiction.