<prompt> Human: Im 23 and have about 10K in my 401K from Fidelity. The Vanguard 2055 Target Date Fund has a 0.08 expense ratio.A couple of CPAs at my work place who are obsessed with Warren Buffet think that I should ditch the target date fund and invest 100 in the SP 500 Index Fund with a 0.02 expense ratio. They say it will outperform any portfolio or managed fund, and that is what Warren Buffet recommends.What do you think? Am I missing out by putting all my funds in Vanguards Target Date Fund? Since Im young should I just go all in in the SP 500 Index Fund instead?Thanks!  <response>: Youre more diversified. Theyre paying a slightly lower fee. The diversification is likely a better decision. 