malaysia is much more cheaper than thai and Bali and cambodia
You can't generalize things. Depends on how you plan the holiday.
For eg Once my wife booked Datai Langkawi luxury family package Mon- Fri for an unbelievable rate. It costs more to stay at home. If I remember right for the three of us less than 500 USD.
They even provided us with a car for free for the entire the stay. I was landing in SIN, Monday early morning and this was ideal. Booked AirAsia from SIN and back. The entire island is Duty Free. Liquor is very cheap, but you are NOT allowed to take any back into Singapore. A Glenlivet was about $15. There are water sports/parasailing/Eco adventure tours etc at very reasonable prices. Also Langkawi SkyBridge/Cable car. It's just a small island but for a relaxing stay it's fine.
(There was Dengue warnings posted even on the beach.)
PS: Also there's a ferry service to Langkawi from Penang.
Just after covid my fife again booked a luxury holiday for one week in Koh-Samui with meals for less than $ 500 for the three of us. Timing matters.
Malaysia is cheap but for the same cost you can enjoy a good resort in Bali or Cambodia if you get the timing right. Depends on the area where you stay too.
For the Cambodia trip we paid only $10 from BKK to PNH and from SEP to SIN about $25 - Air Asia. You need to keep an eye on when the deals are.