For as far back as I could remember, HDB was started off in this way without things like profitibility in its definition. Throughout the 70s (maybe 60s), Singaporean rented HDB flats from the HDB.
Then, slightly somewhat later in the beginning of the 80s (around 1983 ~ 1984) and throughout the 80s and the early 90s, HDB was the sole buyer and seller of HDB flats for dwellers for all I could recall. And there wasn't such thing as a property market for public housing. After those era, what happened next was history.
But if you were to ask me, which generation was happier, I would say, those in the 70s and 80s and perphaps those in the 90s were pretty happy with life as Singaporean. As soon as the ugly head of upward-surging of property prices happened, Singaporean life is greatly affected by it, either directly or indirectly, thus making us more and more of an unhappy nation. To make things worse, there is a relationship between the public housing market and the private housing market!
So here we are, looking back at the basic role of HDB. And I suggest, we should return to the correct initial way in managing our public housing - to serve the nation and her citizen well, minus off the profitability in its equation.