I am assuming you are not aware of the fact that people in USA with Indian ethnicity have higher net worth than any other ethnic group including American born whites. I can only tell you about why I was a democrat supporter when I arrived here as a graduate student in engineering curriculum. It was mainly because the democrats gave me the false impression of being the more inclusive party. They preached "big tent" and all that. I was admirer of JFK and followed LBJ. But soon I realized democrats were keeping me from advancing into upper middle class via progressive taxation. And I have voted republican in every election since 1972. But not everyone is as intelligent as me in figuring out the truth quickly. Republicans/conservatives need to do a better job of public relations.
I agree the gop needs to do a better job in reaching out to the various communities.