Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

How should one structure a portfolio given the possibility that a Total Stock Market Index might decline and not recover for a long time?
John Bogle never said only buy the S&P 500 or any single index Q:Do you think the average person could safely invest for retirement and   other goals without expert advice -- just by indexing? A: Yes, there is a rule of thumb I add to that. You should start out   heavily invested in equities. Hold some bond index funds as well as   stock index funds. By the time you get closer to retirement or into   your retirement, you should have a significant position in bond index   funds as well as stock index funds. As we get older, we have less time   to recoup. We have more money to protect and our nervousness increases   with age. We get a little bit worried about that nest egg when it's   large and we have little time to recoup it, so we pay too much   attention to the fluctuations in the market, which in the long run   mean nothing. How much to pay Q: What's the highest expense ratio that one should pay for a   domestic equity fund? A: I'd say three-quarters of 1 percent maybe.   Q: For an international fund?  A: I'd say three-quarters of 1 percent.   Q: For a bond fund? A: One-half of 1 percent. But I'd shave that a little bit. For   example, if you can buy a no-load bond fund or a no-load stock fund,   you can afford a little more expense ratio, because you're not paying   any commission. You've eliminated cost No. 2....