I've been self-employed for the past three years. Though I did spend my first year out of college working for a three person, now-defunct startup, I've never had a typical 9-5 (or more like 10-8 nowadays) and to be honest, never really wanted one. Lara Schenck, LLC is a profitable business, and every day I do work that is enjoyable and challenging. I make my own hours, take vacations when I want to, and run everything on my terms.
While that's all awesome, what you don't get from working independently is the team experience. I base my work on teaching technical literacy to non-technical designers and content producers so that they can better communicate with developers. The theory is that if a designer understands why it's a bad idea to request 18 fonts, and if content producers know why it's not trivial to edit the titles of a set of related posts, life will be easier for everyone. At least that's my theory, and the assumption on which I've developed my business.