Do not sound like a comfortable retirement to me.
I think one need $5m cash to retire in Singapore.
To spend less in retirement is not a desire retirement.
You have poor financial sense. If you are frugal and live like the nun who retired, S$1m is enough to retire.
Basically you need to put the money in some investments that yield at least 5%... if you live like that nun S$50k a year is enough for a single person. Any returns above 5% just treat it as bonus.