Why do MORE people vote for Democrats?

[Mike]

I identified myself as a Libertarian, which means I'm socially Democrat but economically Republican (don't attack my belief please). I love all the social things Democrats have done, such as legalization gay marriage, marijuana (California), and abortion. I believe in freedom, so I think that people should have the rights to choose the lifestyle they want. However, I completely disagree with the Democrat's economic agenda, which is to raise tax and create a fair wealth distribution (aka socialism). If you have any knowledge of economics, you will know that a high tax rate eliminates business growth, which will eventually increase unemployment. Even though the government can generate more money through taxation in the short run, the economy will decline in the long term, especially for the small business. Also, if government generates money from taxation and spends it, then this practice is no different than communism (government elimination of free-market). Also, high tax rate can almost kill the taxpayers, especially the lower middle class families, which compose of the majority of American families. Yet, these money are spent on food stamps to some who are not even bothered to find a job. I think welfare is a great program for people who really need it. However, it has been completely abused by some who don't even try to get a job. Why bother to work if the government can just feed you? Because of this, it will encourage more and more people to join the welfare program and the economy will just spiral down even more.
Anyway, isn't politics more about economy and money instead of social issues? Even though the majority of Americans agree on the legalization of gay marriage, abortion, and marijuana, it doesn't mean that Democrats are good at dealing with the economy. If so, why are there still more people who vote for Democrats than Republicans? Since Middle Class composes the largest portion of American population, don't they know that voting for Democrats can destroy them financially?
I'll really appreciate it if anyone can answer my question!