There can be a few reasons for this. Waiting time New BTOs are yet to be build or are in the process of building vs. ready-made relatively "young" resale flat. There are people not willing to wait a few years for the flat. So they chose resale Location No one will know the way in advance of the location of the next BTO release. The couple may find the BTO release locality, not to their liking. So they may buy a resale flat. Restrictions Singles can only buy two rooms BTO in a non-mature estate. Whereas for resale, they can buy any in the open market. Proximity to parents There's a grant by the govt when they buy a resale flat close to parents. If they stay close to parents, they can also help each other out more often. If BTO flats are not released close to their parents' home, they may just buy resale. Rejection by HDB There are couples still not getting a queue number for their flat after ten tries. Such couples will try resale. I like for old flats. There are some who find new flats too small. Resale flats before a particular year are bigger than current BTO flats. Near primary school In Sg, criteria for primary school enrollment is proximity to the school. Families living within a 1km radius of the school will often get priority over those staying further away.