If they are SC, fair enough I think.
And even if they BTO, it doesn't really affect housing problem that much, because they will need to sell their resale to someone else in order to buy new BTO.
By simple economics of demand and supply, if resale units are in surplus, their prices would drop.
But no. Resale transacted prices have been rising steadily. This indicates that the demand is higher than supply even in the resale market.
Same situation at the private property market also.
At BTO, resale, Condo, all these housing have seen prices heading northwards, reflecting growing demand and insufficient supply.