I think it's a mix of both; as in intelligence and luck. My cousin told me about a colleague that researched with her professor whom she's worked with all throughout her undergraduate career. If I am not mistaken, it had something to do with chemotherapy and genetics. But the article was published in Scientific American (which is very impressive). I assume it was hard work since the research was very long and arduous. Also, research doesn't necessarily have to result in a "bam I found something" it could be a more in-depth research on an already proven hypothesis that could lead to a greater result.