People tend to see God as a vehicle towards solving their problems or getting what they want.
When you are poor you are more likely to be desperate enough to accept any kind of help. When you are rich you are much more likely to want to solve problems yourself with resources you control, rather than ask for help.
It’s not really that one is better than the other, but rather, how people commonly approach religion and the spiritual, they are far more likely to see the world as ephemeral and belonging to God than they are if they have a great deal of control over self and others.
Less about how much money in a bank account and more about your sense of how control works.