After investing on my own for about 7 years now I've learned several things. Your first Keynes quote sums it up.

1. My combination of ecological/psychological doomerism and consideration of "sustainable" economic metrics (ie, not buying property back in 2001 because I already knew it was a bubble then) has cost me financially, as the market is a group psychological process and little else (ie, not in any way connected to my way of thinking, emotional or analytical).

2. I don't have the financial muscle or insider knowledge to beat the market. The few areas where I can beat the street's common knowledge, such as going long in oil, still didn't work for me - you need a lot of money to buy actual oil contracts, and ETFs like USO are continually dropping vs. the spot price due to market contango. That outcome in particular has really killed my interest in the game of investing.

3. The spots in which I've beat the market were effectively dartboard buys/sells. Over the long run, though, those moves have cost me almost as much as they have made me.

As a result there are only a few things I am willing to do now:

1. buy CDs / insured bonds.
   
2. basic mutual fund plays, such as taking advantage of the bull market and declining dollar buy investing in funds that buy Euro based shares over the past few years
   
3. Currency trading (more to lower my overall risk vs. inflating fiat currencies and general dollar weakness than speculation).

With higher market volatility and a bear market on the way, my interest in buying individual stocks or even mutual funds (beyond bond funds) is pretty much zero.

you are the media you consume.

The quote of Warren Buffett is pretty instructive, not just in the "buy low sell high" way. It is a basic investment realization that market trends are determined not so much by actual prospects of economy, but of perceptions thereof. Surely, perceptions do "neurolinguistically" define much of economic reality - but with limits. Anyway, playing with human perceptions and impulses is frequently easier than playing with economic data.

In particular, fear and greed (as in Buffett's quote) determine most jitters of financial indices. Those market cycles tell more about human patterns of greed and fear than about "inherent" economic structures. I guess American cycles of greed and fear are different from Chinese or other ones - hedge fund modelists may know them all very well. At least those empirically determinable from the statistics up till now.

The flux of capital into asset markets was increasing faster than ever in America, China and other markets. Shares rose not so much because of better buisiness performance (though it is much easier to perform when the whole economy enjoys so much cash Viagra), but just because so many new greedy entrants in Americas, China and the rest of Asia and the world. The common wisdom was to "invest" whenever you have spare cash - and to borrow and invest more is you dare "as a man".

But now perhaps comes inevitable interaction with reality of cash flow sustainability. Still, this year will see a lot of game of fear and greed in the markets. Some ejaculation (if you pardon me) of the dear stiff global economy must be inevitable eventually, but the trigger will most likely be some rational measure to curb financial follies. Libertarian apologists would blame the rational "socialists" or "protectionists", never minding that the absurd sensitivity of the saturated markets is wholly thanks to the "supply" incentives to fuel cash from everywhere into one or few markets.