<prompt> Human: Ive read about diversifying and owning some bonds, but if Im young 30ish with no debt, an emergency fund, and a good salary, why wouldnt I go 100 into SP 500 ETFs? I have no immediate needs for my savings. So why not invest it all in stocks and let the power of compounding work its magic? It doesnt make sense to me to voluntarily reduce my expected return by owning bonds at such an early stage in my career. Am I crazy? Is anyone else 100 invested in stocks? Edit: it looks like a lot of people are 100 invested in stocks. Thanks for all the feedback. Assistant: Why would you only invest in large cap US stocks? Even if you are 100 equities, you should use total market funds and get exposure to the entire world stock market. Imagine if you had lived in Japan and only invested in the Nikkei. Or even if it wasnt that bad, it might underperform the total world stock market.Ok, but you real question is why not 100 stocks? I think historically having a small bond allocation would not shrink your returns much. Also, unless you have held 100 stocks in a severe bear market, you dont know whether you have the discipline to avoid selling off when the market tanks and people around you are losing their jobs possibly you also. At 30 years old I would want 10-20 bonds at least.Feel free to backtest as well: I never go below 20 bonds myself.Human: I believe in capitalism, the U.S. financial legal systems, and American ingenuity. The fact that Japan went through the lost decade is exactly why I want to limit my exposure to global indices. I dont want that kind of risk in my portfolio. The U.S. market has generated consistent returns over any timeframe. It is very resilient and self correcting. Id rather invest in U.S companies that have global operations. That way I get exposure to global growth, but through the discipline of U.S. managers.Thanks for the link to this site. Will certainly check it out.  <response>: Ah, the old American exceptionalism argument. 