Without the housing allowance you will never be able to buy a property in HKG and it will be difficult to put retirement savings aside until captain.
To put it into perspective your career earnings as an expat CPP will be around HKD 18-22 million less as you have to pay for your own rental or mortgage.
Also the above living expenses don't take entertainment, clothing and travel into consideration.
A lot of the SO's have great rosters and most of them travel and explore the world.