People attaining college and universities of different age for different reasons. Some people attained college or university for completing their careers, changing their feilds, for accquiring more knowlegde or advanincing in their particular fields. I will explicate this more following.
After completing High schools people work out on their carriers and choose their feilds to graduate. Some people after completing their high schools start their jobs and donot study further but some people want to specify their professions and to work in some specific field.
Secondly, people who want to earn their livelihood more for that they apply for more education for which they join university. My own sister is an example of this, after completing her B.E, she is now doing master to enhanced her degree so that she could achieve more livelihood for her family.
Some people who wants to change their careers. Their profession, their field, they also apply in universities. These peoples change their profession some time for their choice, sometime for earning more money or sometime to acquire more knowledge.
The other type people are those who are now free and have no job to do and to make there time useful they join universities to learn more.
Some of the people are who join universities just to learn different languages, to know about the world, to learn about the new inventions or to know about the new research of the scientists.
There could be many reasons for joining the university. So one can join university to focus on his life perfectly with all sides.
TOEFL listening lectures: A university arts lecture on Greek drama