I think if the deposit method to increase the VIP level will be easy for gamblers to get.
For example, they make a large deposit and a few days later they withdraw the deposit capital and repeat the same thing. Is that considered valid to push our VIP up.
I don't think they'll let customers to deposit and withdraw that easily. There should be some terms, like wagering deposit to claim it as a deposit meant for increasing VIP level because by simply making a deposit and withdrawal, their VIP system will be abused.
It couldn't be abused since there's a wagering requirement before you can withdraw. IIRC, it's only 1x if you didn't activate any bonus or promotion. So there's a chance that you can't do this 1x wagering requirement. And since this mechanics is quite common in SEA casinos, I doubt they will make withdrawal difficult.*
Some players like this system (using deposits to rank up) more than purely wagering like other casinos.
Disclaimer: only my opinion which is based on personal experience, DYOR & DWYOR