How do some less popular businesses make their owners super rich?

I've noticed that some businesspeople run companies that aren’t very popular in the mainstream, and their products aren’t even bestsellers in the market. Yet, these individuals are incredibly wealthy, manage to donate generously through foundations and NGOs, and still remain filthy rich with grand luxury cars, palatial home etc while being in kerala and not in GCC etc. It makes me wonder—how do they achieve such wealth despite their businesses not being widely recognized or thriving in the public eye? Is our financial system in India designed in a way that allows the rich to keep getting richer? I do understand that they are into multiple businesses. But who advices these guys as to how to generate wealth? Meanwhile, many others who run genuine, quality businesses seem to struggle or get sidelined. What are your thoughts?