I think the big point is that you would not be able to save beyond employer contribution to MPF. I'd argue the same for 3k / month in the US, ironically I've had both salaries, 3k / month in Phoenix and 75k / month in Hong Kong. The other issue you'll have in HK is inflation, it's a real cost. In the US it seems it is less so. Example: Frozen Tyson Chicken Breasts when I arrive were around HK135 (9 years ago) and now they are around HK180.
For 25-30k / month you can get a decent (3bd, 2ba, + maids room) new build in Tung Chung. Your best bet is to meet a few agents and ask them to call you when they sell a unit from the developer to see if the new owner wants to rent it. With negotiating you should be able to take 1k off a month the asking price.
For HK Island, 25-30k will get you a shoebox of dubious quality. My budget was 30-35k. I found a perfect spot for 40k on Littlyton Road, but she would not negotiate, and it had no view. I found new & tiny with amenities in Kennedy Town, where I ultimately ended up (714 sq ft, 3bd, 2ba, buiding, pool, gym, near MTR). I also found large and really old. For 30k I found a 1400 sq ft in Sai Yin Pun, but the baths and kitchen were so old, the pipes to feed the faucets came through the window to the taps. I also found 1100 sq ft, renovated bathrooms, but very old kitchen, for 32k, in Sai Yin Pun. Wife wanted amenities so we went to Kennedy Town.
For families, unless you are receiving assistance for schooling forget it. The debenture alone will bankrupt you. We just had triplet daughters (4 weeks old now) and will likely move out of HK when they are 2. The cost of a school ranges from 8k to 14k / month, and schools seek donations on top of that. Both my wife and I work, but we would have been here 11 years by that point and it would be time to pass the torch to someone else.
80k & Single? Hell yeah--until you marry and have children.