Why is there so many producers, co-producers and executive producers in a movie production?

Ever see the movie credits at the end. You'll see every person, in or near the movie while it was being filmed. I mean seriously, what are there roles, verses a director, co-director and whats a boom operator? I took video tech in high school, for two years, I loved making films. How would I get a job being a special effects sound person. Ya know in a movie, especially animated, there is people in a room being recorded with all these gadgets to make noises and such in the movie. Do I need a degree for this? Just wondering, Or do you have to know someone, that person knows someone and so forth? Then ya get the job? Are there studios in every state? or just , Cali, NY, FL, Las Vegas, and Chicago? Just interested in this Hollywood film stuff. Hey and does someone get paid to find the bloopers.