CPF is flushed with cash pouring in from all over the world, thanks to the uncanny geniuses running TH and GIC. We probably have more cash than the average columbian drug cartel and don't know what to do with it. How else is the PAP government able to guarantee 3-4% per annum to all CPF holders for decades regardless the economic situation?
In most western countries with pension schemes, cracks have already surfaced and the government either has to resort to pension cuts, outright defaults and bank runs, or to issue more and more bonds to cover their deficits.