Realistically he was just the right person at the right time with the right ideas to make a righteous mess and end and ruin so many lives in a surprisingly short timeframe.

Also worth remembering that Hitler took heavy inspiration from Benito Mussolini, even coming to visit Mussolini early on to take inspiration from him (and later propping up Mussolini once the anti-fascists got too successful) even the Nazi sulute was inspired by Mussolini, who had lifted it from a series of silent films about a Roman hero which those films had likely invented the concept of the "Roman sulute" in one of the earliest examples of Hollywood fiction influencing reality

Hitler himself was unique, so there's always value to studying what made him that way. Even if the research shows his genes aren't relevant to his evil, that's a valuable finding.