Since 2000, about $108 billion in returns on our reserves (NIRC) have been used to supplement government revenue (image below).
Although NIRC is supposed to benefit citizens, the reality is a high percentage of this ultimately find its way back to GIC via CPF contributions or funds set up by PAP under many different names.
Excluding Government Securities Fund, PAP has set aside $159 billion to meet future liabilities. (Statement of Assets and Liabilities)
To a lay person like me, this appears to be a right to left pocket transaction. Not 100% of course.