Why do I fear my future after college? Did you ever feel this way as a college student?

I just finished my freshman year at a major state run university with a good GPA, and a double major in Political Science and English. My original major was English and Film Studies, my intent was to go to grad school at either USC, UCLA or NYU and receive a MA in film with the hope of screenwriting and directing Television and Film. I backed out of Film Studies but kept the English Major, and added Political Science. I am good at political science classes and my political science department at my university is really, really good. What I fear about life and what I will become after college is some middle ranking employee at some law firm or company living on a salary between $50k and $100k with a ranch house in the suburbs, working until I retire at age 65 and then buying a RV or playing golf until the day I die wondering what I did with the last 40 years of my life. I want to leave a legacies more than anything, the whole reason I wanted to become a director and screenwriter was to leave my films for future generations, look how people still love the film Casablanca nearly 70 years after it hit theaters. Now I'm considering getting rid of my English Major and adding Psychology with the goal being a PhD in Neuroscience, I like neuroscience but I don't know if that's what I want to do with my life. One thing I enjoy doing is building websites but I don't want to do that for a living unless I was the CEO of my own website, kind of like Mark Zuckerberg, I would never want to sit in a cubical and program computers all day every day. I think my biggest problem is that my interest change rapidly, I mean just last year I planned on majoring in Physics or Math, I feel like I could major in anything at my university which is a problem. I have spent my entire life so far studying thousands of books and manuals. My friends all seem happy with the careers they hope to one day have, for instance one of my friends is going to for an MBA starting in the fall. Now I don't know what to do and I'm going to be a sophomore in the fall with no idea what to do with my life, all I know is I don't want to be just another average person to live life to just simply exist then die.