People change because they need not because RM is 3.1 or 4.1
If I can wait, I will definitely prefer to change at 4.1. How about you? You might be the type who change and spend all the ringgit immediately, but I'll hazard a guess that the majority who visit Msia more than once per month are not like that.
Also, others may change a far bigger sum than what you change, or for that matter, the difference it makes is very big to them.
It's like why some people wonder why Singaporeans like to risk limbs and life to shop in JB just for some peanut savings. To them, the savings is not significant.
Why are people so concerned if RM is going to be 3.10? Are you trading the ringgit?
We are trading currency here, sell SGD to buy ringgit. If it is going to go up to 3.1 soon, why should people kam gong go and change at 3.04 if they can wait?
Not everyone spends all the ringgit they change during one outing.
Those going to JB or any part of Malaysia, be it for shopping or holiday, will always need to keep ringgit.