AFAIK one of LKY’s stated goals was to compete with private corporations for the best talent by paying comparably. DPMs are paid quite handsomely but not incomparable to C suite pay at large companies.
>Singapore's ministers are the highest paid in the world. Prior to a salary review in 2011, the Prime Minister's annual salary was S$3.07 million, while the pay of ministerial-grade officers ranged between S$1.58 million and S$2.37 million.