That is the builder doing that, presumably having gotten sufficient orders to proceed with construction.  The legitimate customers are those who are going to use the product as intended ie live in it.  

Housing is a long term consumption good, not an investment that will generate additional real output.  Any increase in value is inflation and income from this process is simply a transfer - ultimately from the lower classes to the rich.    Effectively, speculation constitutes a tax and there is no value added.

Cheers,
John Meyer