https://en.wikipedia.org/wiki/Special_Marriage_Act,_1954
Obviously, just like mixed race marriage took a while to be culturally accepted in the US, it is a similar situation in India.
More importantly, it almost always comes down to socioeconomic class rather than caste or race. The upper socioeconomic “castes” or “tribes” or whatever you want to call them have been inter marrying forever, and no one cares.
I would easily bet if a Brahmin kid brought home a significant other worth a billion dollars, their parents would not give a crap if the SO was a lower caste person. By definition, just being worth a billion dollars would somehow elevate them out of their caste. Same with white and black and Asian and Latin American or any other tribal designation.
My take away from this is that there is nothing natural about one caste having an advantage in business, that success in any field has much more to do with who has financial and social capital than with what caste someone is.