There are many reasons why I decided to go to 'I-school' (that term still makes me giggle) and pursue an MLS. Some of them center on my personality and talents; some are characteristics of the profession.
I've always enjoyed teaching. More accurately, I've always enjoyed most aspects of teaching. Helping people find the information they seek, filtering through material to find nuggets of interest, those amazing (though a bit rare) "aha!" moments when things click into place - to me, those are the great parts of teaching.
Unfortunately, there were also aspects I did not enjoy much. Like the difficulty of deciding what to teach and what not to; the problem of selecting topics that would give every student in class the information they needed. Grading can be very time-consuming and not too fun either. The issue that rankled me most, though, was the question of assessment. Even when I did construct a good exam or problem set (a surprisingly tough task), I was still doubtful. Was it really a decent indicator of what people had learned? Or was I just figuring out which students were good at taking tests?
Those negative aspects have been enough to keep me away from teaching as a profession. Library science seems like a great way to maximize the parts of teaching I enjoy while minimizing the ones I don't.
To borrow a phrase from Richard Feynman, I've always loved the pleasure of finding things out. I adore researching and learning new things about all kinds of subjects; I enjoy the thrill of the information chase. If, as Roy Tennant suggests, "only librarians like to search, everyone else likes to find", then I am definitely a librarian at heart.
One of the things I love about the field is the huge variety of specializations and niches available to today's librarians. I am still sorting out which areas are most appealing to me - I am drawn to archives, to digital libraries (especially digital preservation), to academic science libraries and more - and it thrills me to have so many paths to consider. My current field definitely does not offer this many choices, certainly not at the master's degree level.
I am impressed that so many folks retire out of library jobs. I think it's a great sign that people are content and fulfilled in their positions to the extent that they stay in the field until it's time to stop working entirely. This is something else that my current career lacks; lab technician jobs are often thought of as a way to gain experience for a few years while waiting for something else to happen (grad school, medical school, etc). It's not exactly a profession that grays. I have been quite happy working in labs and doing research for a number of years, but even I can't imagine wanting to keep at it until retirement age.
I was surprised to discover that I immediately felt at home with my fellow MLS students, faculty, and librarians. We share similar viewpoints and values, and it really seems as though I've found my people (as admittedly hokey as that sounds)! It's not that I ever felt so different from other scientists, just that I seem to have even more in common with library types.