Certain types of crimes and scams tend to gravitate into certain demographics. This community is full of drug dealers, that community is rife with protection rackets. This other community tends towards phone scams. There are particular circumstances that have lead certain scams to be rife in Nigeria, and another that have led this sort of scam to operate in India.
It’s not necessarily that Indians generally are more corrupt or venal, it’s just that this is a particular way venality and corruption manifests over there. Other communities manifest their venality and corruption differently, due to different structural reasons. So the simple logic that goes this is bad, predominantly only people from this demographic are doing it, therefore this demographic must be worse than everybody else, is overly simplistic. There are bad people everywhere, they just do different things depending on their circumstances and opportunities.
What are the structural conditions you are referring to.