A decent salary is one which will cover your expenses and allows some savings.

For eg, when starting out as a single, you will find that $3.5k is quite decent. For $8k pm, you will be working 10-12 hr days.

Later when you get married, buy your first BTO flat, without children and without car, your combined HH income of $6K - $10K is also ok.

In your 30s, with children and a car, a decent HH income should be around $8k - $15K
I know many grad couples in their 30s cannot qualify for BTO flats, thus their HH income must be above $10K.

From here on, many will have to decide whether they want that promotion with higher responsibilities, longer work hours but much higher pay or continue with their current portfolio of responsibilities, regular work hours and less pay. Many will choose to go for the promotion which can see them earning $180k or more pa. in their late 30s or 40s.

Those who can hack it, are still in their jobs (in their 50s/60s) earning above $250k pa or more. And they are still working alongside their peers who either didnt get or chosen not to get the promotion and ended up earning $150K or less pa ! Believe me, when you see the families, both sides are happy, except that the higher pay ones can send their children overseas for uni studies and not worry about their retirement adequacy.

The important takeaway here is earning big bucks and good health and happy family is not mutually exclusive. Conversely you can be earning low pay, have poor health and have a broken family. You must avoid this at all cost!