Because renting it is extra work and extra risk. You have to deal with finding someone to rent it to and then you have to keep inspecting the house to make sure

Because renting it is extra work and extra risk. You have to deal with finding someone to rent it to and then you have to keep inspecting the house to make sure they haven't wrecked it and then you have to fix any issues they report. Where as buying and selling later is very low maintenance.