It's worth noting that the S&P failed to overcome the 21ma.
Cheer up already. Longer term, the boomers retire and there won't be enough workers to get done what needs doing. A mere 30 years ago we valued mostly things, things we can touch and hold. Today we merchandize intangibles, information, intellectual property, bandwidth, apps, the "cloud". Just think of how much the world has changed in the past 30 years. Material sciences are about to revolutionize the way we build things; carbon-based materials, graphine, nanotubes. Buildings and bridges built of flexible carbon members instead of heavy rusting steel. Homes and buildings lighted with LED's and heated with ground-based heat pumps using solar energy stored below the frostline. Longer term, the bull market of the milenium begins. We may dip to SPX 830 but it will be the buy of the century, the final leg to a breakout of the consolidation which began in 1999; the great transfer of wealth from one generation to the next.
That does get to the root problem, which is that the demographics of the developed world and even in China, are skewed way too heavy to the post WW2 babies.
Boom has gone bust and although the larger problem is the very unsustainable nature of a global economy which is built on the notion of endless growth, the immediate issue is the need for the old people to die.
America was able to fool itself into thinking that endless growth was possible, due to the post WW2 hegonomy in manufacturing and the need to rebuild those other countries.
Jeremy Grantham thinks that 1.5B is the right number of people and he tends to be right about a lot of other things so over some period of time may be right about that as well. Technology likey enables a larger sustainable number of people, but technology itself is resource intensive, so maybe not.
Like all other bubbles, this 100yr people bubble will end, badly.