Sky high rents

Recently, everyone will say, "Don't buy property now. Wait till the market crash..." or "House prices are now sky high. Rentals have also gone up."

Came across a rather surprising article on Yawning Bread, about the ST report on sky high HDB rental prices. Yet, although I think such mistake are really unforgivable, the trend of rising rents is a fact, for both private and HDB houses.

Massive En-Bloc developments reducing properties available for rental Ex En-Bloc home owner who are cash rich and willing to pay Home owners who are not willing to rent out property hoping for En-Bloc sale

All these factors coming together, not only greatly reduces the supply, but also increases the demand. How can rents not rocket?