Why not consider the traditional ways of earning passive income through stocks, bonds and properties?
I know this part wasn't addressed to me, but I'll answer.
A 1M portfolio yielding 3% or 4% will give you $30k or 40k annually.
Yes, today, not guaranteed. See for example Japan, another demographically challenged country in Asia, which has experienced 30 years (and counting) of not having those yields.
3% to 4% is not a difficult target to achieve.
Until it is.
If you happen to die early, those assets will be passed on to NOK.
Yes, OK, that's one choice, but (as I keep reminding everyone) why make your loved ones wait? Shower them with money and affection now.
The only reason you're making them wait is because you have to hold back tons of reserve to self-insure against longevity risk. And/or you make yourself wait to take that fabulous cruise you always wanted, or to dine at a 3 star Michelin restaurant in Italy, or whatever.
There's a reason so many wealthy people like high quality life annuities (via trust funds): it's utterly liberating. You don't have to wait to give your loved ones both money and affection, and you can have as much fun as you want out of "normal" savings and investing. Because, no matter what happens, you'll be at least OK to a foundational standard of living. You too can think like a rich person and act much the same way, even if you're not rich.
AND it's OK to save/invest slightly more aggressively -- and in higher yielding fashion -- when your downside lifetime risk is limited. This is one of the major advantages of traditional CPF and CPF LIFE, properly understood anyway. CPF should properly count toward the bond/bond-like part of your portfolio when making investment decisions during the course of working career.
....Anyway, I suppose you
could try to self-insure. But if you try to do it all, on your own, then it's just flat out more expensive at least while you're alive and/or makes life somewhat more miserable (or at least less enjoyable) for you and your loved ones, because you're always worried about survival and losing it all rather than relaxing and enjoying life.