Despite your best efforts, there are numerous reasons why you might decide to transfer colleges. Plenty of students, for one reason or another, might find that they're unhappy with their first choice college, or maybe the school they ended up attending initially wasn't their first choice anyway, and they want a second shot. Maybe they've discovered that their current school doesn't have a strong program in their major or area of interest, or perhaps the student simply wants to save some tuition dollars by transferring to a less expensive school closer to home.
Transferring colleges can be a great move if you're sure that the new school offers opportunities your current school lacks. That said, transferring involves an application process (often including procuring another set of recommendation letters, resubmitting test scores and writing even more essays), and competition for open spots can be fierce, especially at prestigious and highly-selective schools. There are also some key differences you'll notice from applying to colleges the first time around.