Should i be investing my cpf money? Or keep it in cpf to yield the interest?

I simultaneously aim for FRS in SA, and invest with OA. Once reach FRS, I suppose I will shift more to invest.

I did both. Invested some of my OA on some UTs. So far it can beat OA 2.5% interest, but I leave my SA intact.

Not a financial advice yah. DYODD!

What about my parents who are around their 50s? Should they invest their CPF with EndowUs or just leave it till their retirement?

I invested as much as I can from the OA with EndowUS, and let SA collect the 4% risk free.