Remember in 1999, RM500 and RM1000 denominations were demonetized.
At that very moment, Malaysia's Central estimated that there were over RM4.3 billion worth of RM1000 in circulation.
That was a huge amount 17 years ago
The elimination of the big denominations is to make it harder for people to carry millions in their brief cases. I'm sure even Najib could have carried RM$1 billion in $10,000 notes out of Malaysia.
What surprised me is that the PAP discontinued the $5,000 & $10,000 notes? It made it easier for me to transfer $ from one bank account to another without paying for a draft. The only large note left in Spore is the $1,000 note & that's usually what I take to Thailand because I get a higher exchange rate in Thailand.