1: It was a mathematics example to illustrate how crappy Social Security actually serves the people. Besides, Social Security already takes 15% (7.5 directly form the individual), my example only shows what COULD have been done with just 4% (using all 15% the value is almost $5 million). As for showing the math, I have already given you all the variables and you can find the formulas on the web easily, though it is just as easy to find a calculator and skip the math by hand.
2: Contrary to what you believe (I seriously doubt you know very much at all about it) long term investing in the "evil" stock market (most easily through mutual funds) provides easily predictable long term gains. Yes there are short term fluctuations, and also methods to deal with them (beginning with not putting any money in there that you might need in the next 5 years).
3: No we can not simply end Social Security tomorrow. But there are many different ideas on how to continue to support the people who foolishly allowed themselves to be dependent on it. Without trapping a brand new generation into something that is just simply BAD.