I sold a 48" Raptor SD with zt2800's and 74 hours with the same engine you're looking at for 3K about 3 years ago. I know they've made some changes to their models so not sure how the build compares anymore. But seems comparable.
I used it for 2 summers, bought more property around our house and bought a bigger mower. Someone may have bought this and decided it was too big for their yard, or not big enough. Residential use doesn't put a lot of time on a mower and if he just had a half acre or so yard, that could easily be an entire summer of mowing in that short of time.