I'm relating what I was told. However, I have no reason to disbelieve this figure based on my own experiences.
If my memory serves me well, close to $2,400 per month was going into my CPF account monthly. Then there were contributions from 13th month bonuses plus additional end of year bonuses based upon company and personal performance. Commissions were also subjected to CPF deductions.
My cousin worked in banking for many years before he retired in his late 40s to do his own consultancy work. 6 to 8 months bonus was the norm during the good years and 2 to 3 months was typical of the quieter years.
If you do the sums, it works out. $2000 per month (employer plus employee estimated) x 16 months (12 + average 4 months bonus) x 25 years = $800,000 without adding the compound interest.