Why are we doing this? I can only speak for myself, but here's what I think.
Wall Street was the perfect target, as its the heart of the evil or disease that has infected America. We live in a country where money dominates all. Money dominates our elections. Democracy has been pushed aside in America to make room for a government of money, by money and for money. The candidate with the most money almost always wins. Politicians certainly believe this, as they want to win and thus they spend their time accumulating donations and talking to people who can give them large quantities of money. Basic American concepts like "one person one vote" have been discarded for a world where money has been legally equated with free speech and corporations have taken the rights of freedom of speech as rights of their own.
Everything in America is for sale. Everything in America is dominated by money. The location of the OccupyWallStreet encampment speaks volumes to this, as old "Liberty Park" in lower manhattan, near where George Washington was sworn in as our first president, and home to the OccupyWallstreet encampment is no longer a public park but has been sold to a corporation.
We live in a country where money makes all decisions. Since elections are dominated by money, our representative bodies and our Presidents, Governors and Mayors all serve money. One gets the distinct impression that the only bills that pass and become law are those that make someone more money. Politics today is more an exercise in fighting over who gets a share of the public money, taken from us with high taxes, than an exercise in democracy.
When we as a nation try to talk about helping the unemployed that have lost their jobs when Wall Street crashed the economy, the political debate is entirely about money. When we as a nation try to talk about giving health care to all Americans like any other civilized nation, the debate is distorted so badly by money that the bill that results could have been named the Big Health Corporations Profit Protection Act of 2009. The one thing that was obvious from the 'health care debate' is that the bedrock that all of our money dominated government could agree on was that the profits of the big corporations in the health care field had to be protected and guaranteeed. Health care for Americans was obviously a secondary concern.
And this is why we occupy. We live in America where its been made very plain that the lives and well-being of Americans is now of secondary (or lower) importance than profits for Wall Street. Across America, citizens are losing their jobs, losing their homes, losing their life savings, and denied health care because profits are much more important than people.
We want an America that is a democracy. That is once again a government of the people, by the people and for the people. We want an America where every human value is not sold for profit. We want an America where if one is sick or injured the first questions asked aren't 'how much money do you have to pay for it?"
That's nothing new. The original American revolution was a revolt against all the big money mercantile interests that had aligned with the King of England. The Boston Tea Party was as much about the East India Companies monopoly on trade as it was about tea. And, when the King and Parliament passed the Punitive Acts that tried to close Massachusetts democratically elected courts (that decided things like foreclosures) with officials who had bought the judgeship from the King of England, citizens of Massachusetts came out in the thousands and met these judges and just said No! That was the real beginning of the American revolution in the summer of 1774.
We want our country back. We don't believe that Wall Street should own America. We do not believe that every question and every decision should be made on the basis of who has the most money.