Let's take an example:
People go on studying after high school for many reasons. Some of them attend college to have a degree, others in order to increase their knowledge and few people because they just want to be in touch with others.
You start with saying many, but then give three, which I think doesn't count as many.
How about something like this:
There are three main reasons for continuing studying after high school. Some people look on a degree as a qualification that will further their careers, while others view tertiary education as a way of broadening their knowledge.