What is your definition of success? You don't need a degree to go get an entry level position paying 17-19k p/a (in London.) Play your cards right, work hard, within ten years you could be on 30k p/a. There's a certain amount of luck involved as well. In 2006, when I was 18/19, I landed a job at al-Jazeera running their tape library and was earning 26k p/a. That was in boom times, and at a pretty rich media company, but it was still a pretty decent achievement. So it can be done.
You don't need a degree to go start your own business, write a book or screenplay or any other multitude of things. It's drummed into people during school that they'll amount to nothing if they don't get GCSEs, A-levels, a degree but, in all honestly, that's just scare tactics.