Actually, expected returns will be slightly lower but well worth it as the reduction in risk from the diversication away from 100% equities is huge. E.g. 20% in bonds will barely diminish expected returns whilst significantly reducing your overall risk.
Not always true, According to WSJ http://blogs.wsj.com/marketbeat/2011/02/07/depressing-chart-... "Through the close of trading Monday, the investors in 7-10 year Treasurys would have seen a return of 76% percent over the last 10 years, versus a return of 17.4% for stocks. So you could have socked your money in supersafe U.S. Treasurys and reaped a risk-free 80% gain. "
