Should Investing Be Long Term and Boring?

Peter Lynch once said most investors would be better off in an index fund. Rob Arnott's fund beat the S&P 500 by I think 30 basis points, but it was 20% more volatile. If smart beta is good, and that means it beats the index, then dumb beta is does even worse than the index, right? So smart and dumb are different. But why are people going to be dumb if it's so easy to be smart? It's just another claim that I can do this better.