Stock markets are more than just "tools to accumulate welath in only a few hands." They evolved out of business' need for capital as well as investors' desire for better returns. They serve a function quite well and, in fact, are far more democratic, not to mention more effective, than the old way of raising money which was simply knowing a king or lord.
that's a complicated question. Wall St has always been full of people "too smart for their own good." Of course, wall st's washington alliance is what keeps it the center fo the universe...otherwise finance might be much more spread out. anyways, to some extent it was the fed's fault, providing enormous amoutns of excess liquidity (monetary inflation) which is generally what fuels such speculative excesses. Once the deed was done, the Fed felt that allowing BS to fail might cripple the country and stepped in, for better or for worse.
Capitalism, at it's most basic, is the free flow of capital which allows for its employment where it's most profitable. the concentration of capital (or accumulation of capital in fewer hands as you put it)is a marxist theory. Simple accumulation of capital (meaning, anyone can accumulate) is, of course, hwo capitalist functions and how decisions are made to allocate between consumption and investment. Capitalism, like any ism, is subject to the quality of people and institutionswithin which it functions.
BTW-I paged through the NG China issue at lunch, nice pic's. I didn't read it though. TO your earlier point, wealthy economies can "clean up." Your information on pollution deaths woudl be more meaningful if coupled with deaths from malnutrition and a "hard life." There was very little industrial pollution in the middle ages yet most people never made it to what is now considered middle age.

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