How do you know if university is right for you?
What do you want to do with your life? University is one way of getting to some of the answers. Trade school or apprenticing is another, if you think that's closer to what you want to spend your life doing. 

It's also legitimate to say you don't know yet -- in which case you need to decide whether starting classes would help you decide what interests you, or if doing something else for a year makes more sense.

I knew what I wanted to study (or thought I did; turns out I was close but not on the mark), but even so I decided to take a year off before college; I needed a bit of maturation time, and to switch from being the youngest in the class to being one of the older kids, for my own comfort. Spent the year doing volunteer work in a hospital (electronic repair, "biomedical engineering"), which was certainly educational in the general sense, helped build my self confidence, and may actually have helped my college application stand out from others.

"... There are nine and sixty ways / of constructing tribal lays, / And every single one of them is right!" -- Kipling