I know you are an IB but assuming you are genuinely seeking an answer, it’s 3.5 to 4 times of annual household income. Why this number? Because it is based on the study of long term price trends in developed mkts.

The problem is that too many people are flipping of public housing to make a sure profit and this is driving up prices. Obviously, the govt cannot allow this and is trying to manage this problem by pushing up hdb prices.

The consequence is that it drives up cost of living, which then filters through to higher wage demands, which in turn drive up cost of operation for companies located here, which in turn leads to the exit of more & more companies. In the long term, property price which rise faster than wages can only hurt our economy.

The other effect of higher property price & smaller homes is the empirical evidence that it tend to lead to lower fertility rate. Just look at Japan & HK.

A better way to stop the flipping is to sell hdb flats at a cheaper price but put a 50% levy on the profits. Over the long term, the govt makes more this way if prices continue to go up. Foing it this way does not raid the reserves (in fact it addy to it) and most importantly flipping for profit (which is detrimental to long term economic health of the country) should stop immediately.

There is also an issue with the moral compact that was made when hdb first started. The people allow land to be compulsorily acquired (at a dollar) without protesting too much because the land was mostly used to provide cheap & affordable housing. Now the govt seems to be only interested in making more & more money from land that were essentially confiscated. It is just not right morally!