Because you only lose around 0.5% if you go the long route while you lose min 3% to banks if you use their service.

Nope. Because the loss will only be at RM to SGD. After the money is in SGD in SG, you use local transfer SGD into IBKR. Think of it if you use Duitkow, any losses? No right. Same now. IBKR offer you real time market rates to convert your money for only USD2. Hence no markup, no additional fees apart from USD2.

If you want to save more money, you can manually select the exchange rate you want inside IBKR to change money and wait for it hit Vs using market rates. So far I have always use this approach of set and wait to get more foreign currency Vs convert once I have SGD inside my IBKR.