If you all can remember Gemini Cheat Fund then you will realise this CPF is almost the same. The scheme will only work as long as members contribute. Once there is a stoppage, the whole thing will collapse.
It's even the same with US Social Security funding. The government of the day gets to spending this generation's funds first. The next generation tops it up to pay the last generation's retirement benefits. Many Singaporeans may be political silent but not stupid. They banked all their CPF on the biggest and most expensive flats available and affordable to take the money away from CPF to HDB. Trouble is unlike in US, in Singapore CPF and HDB are right pocket and left pocket of the same pair of pants. HDB just keep finding ways to increase housing prices to deplete your CPF funds since you're so bent on using it. Both CPF and HDB surpluses will go to the Treasury, Ministry of Finance, GIC and Temasek anyway. They can spend or speculate or lose whatever. The next generation foots the bill.
In the early 1990s, MAS allowed CPFIS for CPF members who have paid-up homes or didn't intend to buy homes to invest in shares and unit trusts with their CPF funds. That's was due to international financial market pressure to keep Singapore presentably as a financial hub. That's nothing new or innovative. US has allowed Individual Retirement Accounts and UK has allowed Personal Equity Plans years ago for retirement planning with tax privileges within brackets.
By the mid 2000s, most smart Singaporeans realized the scam again and after housing, banked all their CPF balance net of housing into shares or unit funds. That took control of investible funds out of government hands. On the negative side, yes, you lose money is your business, can't blame government investment agencies since you're making your own investment decision. By the late 2000s, the hefty losses sustained by GIC and Temasek in international investments caused them to shift goalposts again. Now CPF members must keep minimum balance of S$40,000 net of housing in order for the funds to be personally investible.
You still won't see your money though. That's to make sure that most have enough to pay for the CPF Life scheme. On top of that, sick or not, you need to maintain above S$30,000 in Medisave. If you're not sick enough to be warded, you can't pay through Medisave too. What should you do? Collect cans and cardboards!
