AdvCash caters to a clientele that does not mind (or has no other option than, or even prefer) working with a financial institution from Belize. They are not competing with Wise, Revolut, or most other EMIs.
Belize is more "flexible" in terms of regulating companies, especially when it comes to card issuance. Also, Belize doesn't have geographic restrictions for onboarding clients (as long as they are not from Belize). It can be an ok jurisdiction depending on how you use it.
if you have plenty of money you will not fail to establish a business there. It requires hundred of thousands of dollars to get setup. For AdvCash it must have been no problem at all.