Why

Because it must be like that. Many students stop studying, just because they feel bored and do not match with their scientific field.
Why? Because the first time when they choose their field of scholarly take, does not comply with them. That's due to a lack of self-introduction, but it does not mean there is no success without self-evaluate. Many also work with a field that is not their passion, the desire may be because their parents and an other layer. Coercion against something that is not preferred, sometimes the first step is a success of your future, so do not consider forcing a major disaster for your future.
You live in this world alone, many people around you, and that is the nearest family. You can rate yourself. For example your parents, they are raising you, and they know more than what you think, and it can be a great asset for you to choose the university and the scholarly field that you take with a little advice from them.