For me, I've always seen myself in school. I never really knew "what I wanted to be when I grew up" but I realized as I was going through school and then college that my passion is learning. I love to learn and expand my knowledge and challenge myself. I am one of those people that is good at almost everything- you know, can pull out the A's and an occasional B in math but hate those classes with a fiery passion. I love languages and thought that I would be doing something in that field but I eventually changed my major to history because I love understanding why people do and see the things the way they do. With grad school, I can use my language skills with the primary sources and study something that I really love and continue to study it for the rest of my life through research and teaching classes to young adults.
Of course there are other benefits, such as basically getting paid to go to school or "avoiding the job market". But in all honestly, I would love grad school despite its difficulties. I'm more than capable to go all the way with it and it's not just something I need to get out of the way for a certain job I want, I'm actually looking forward to it (but am still waiting on admissions decisions). My area of specialization gets a bad reputation for being dull and stagnant and I think it's important for those who want to be professors to show passion for their subject so the students can get excited about it as well.