In the other thread a reader share he sold his shares and got USD 200k and convert to SGD. 200k in your definition is small monies I would presume?
It depends on what it’s for. If it’s for a house or for a retirement in Singapore it’s (unfortunately) not a lot these days.
Some people need to understand the power of compounding.

If you invest $1k a month in IBKR at age 25, when you reach age 60, you will have quite a lot of money. Depending on how the stock market performs it could even exceed the SIPC protection limits. (If you are on IBKR SG there is apparently NO SIPC protection)
Brokers in Singapore have no comparable coverage to the SIPC. So what are you talking about?
I wrote “SRS.” The SRS contribution limit is $15,300 per year, more than $1,000 per month. Did you just miss that? Interactive Brokers cannot do anything with SRS dollars. It cannot do anything with CPF Investment Scheme dollars. It cannot hold your Singapore Savings Bonds. Tautologically you’re going to have other asset custodians. You have to, really.
On the other hand you could actually hold a much greater fraction of total household wealth at FSMOne or Endowus (as examples) because they can handle CPFIS and SRS dollars. Are you now going to post about the over concentration perils that could actually exist in the real world with those brokers?
I'm a big fan of IBKR but doesn't mean I'm going to give them all my money.
Who said you should? Who said you
can?
But you don’t have to name any specific broker-custodian in that sentence. Don’t keep all your assets with any single custodian. Simple.