What to do with $500K spare cash?

Maybe can share how you get $500k? Doubt one can earn that much, from parents?

There's so much you can do with 500k.

Get settled on your insurance. Critical Illness, Life Insurance (In case of unforseen death), Personal Accident and Hospitalisation Insurance (Integrated Plan on top of Medishield)

I believe in CPF. Many Singaporeans will not agree with me. There's a movement in SG called the 1M65. Basically it is maxing out your CPF SA asap. And let the risk free 4%pa compound and grow to 1Mil by the time you're 65. You'll enjoy high monthly pay outs from CPF. Of course you won't benefit from the 1Mil. But your Cash Nominee will when you pass on. Full cash will be transferred to your nominee.

You can invest in roboinvestors. I recommend Endowus or Syfe. I personally don't like Stashaway due to its heavy SG portfolio.

Apply for Regular Savings Plan (RSP) to buy top ETFs monthly and let it compound along with the effects of Dollar Cost Averaging (DCA).

I've heard of an Investment Plan by an insurance company (I think is NTUC/AIA/Prudential or Manulife) where you put in a huge lump sum of 100k. Gives you 8% pa that pays out monthly. That's about $600 of passive income a month. If you don't want to take out the $600 monthly, theres an option to let it compound. Dont have much details on this.

With 500k, I'm sure you're a priority member to banks. They should/may have an Relationship Manager (RM) tagged to your account. Request for a meet up and seek financial advice.