10% puts you in S&P500 territory before expenses. That makes it real but still a tough goal to beat. 3/4 of professional money managers don't beat the S&P. The reason behind that is that people love to make money but they hate losing it way more. That leads to diversification and ultimately to accepting less than the 10% in return for lower volatility. The more money people have at risk in their 401K, the more this appeals to them. Each 401K differs but most only offer a conservative portfolio in the first place. Some also offer only ones they get a kick back from. By the way you can see how your 401K plan compares to others at https://www.brightscope.com/