To realize when you're unhappy somewhere is the first step, but taking action and realizing you don't belong somewhere is why transfer students have the guts to do what they do- which is for themselves and their future.
Starting college is a brand new beginning for everyone. You're placed in a different environment, with a diverse group of people, and amazing opportunities and experiences waiting to be unraveled. Starting college as a freshman, everyone has this picture perfect image in their head of how it's going to go, what they will experience, and what kind of people will be a part of their life. Although it's awesome to have goals and aspirations in life, (which is basically the point of college- you're there to educate yourself and get a degree) , your college experience will take so many twists and turns, in good ways and in bad ways. What a lot of people forget is how your time at school is shaping the person that you will become in your future, and that those experiences (even the bad ones) are happening for a reason. You can't grow and shape yourself if you don't like your school- the environment that is intended to make you do that. There are a lot of warning signs you should be looking out for as a newcomer in college to see if you're actually happy at your school.
When you don't belong somewhere, you can isolate yourself.
In college, you want to find a group of people who you connect with and who share the same values as you. So when you feel no connection with people at your school it disrupts you from opening up and discovering new things about yourself.
The environment is just... blah.
A college campus should give you a sense of home and comfort. Yeah, you probably want to set it on fire the week of finals and midterms because you're just over it all, but the environment of your college campus should make you feel like you're in the right place. Everyone has a gut feeling when they know something just isn't right.
Campus culture sucks
You may want to transfer because the college's efforts in making the experience enjoyable just suck. Sometimes people need some guidance when they first get placed into college, (nothing wrong with that because some of us don't know what the hell we're doing). If a college doesn't have any opportunities to get you involved in campus life, or it doesn't have any activities that you're interested in, then you'll end up getting bored every day just focusing academics. You always want to broaden your horizon and try new things in college, that's part of the experience.
Some people transfer for other reasons like academics or money issues, things that don't involve being happy or not. If the issue is your own happiness, then take it seriously and reconsider your choice in school. I applaud anyone who goes through the transfer process because it's a hard thing to do, and to admit to yourself. Even though it may suck at the time, you really do gain so much experience from it all (and you can say you've attended two different schools!).