What are some of the advantages of entering the university as an adult student?

As an adult, with any luck you have some kind of employment and income, so you are not dependent upon student loans. You also will probably have learned at least some useful information, in the years that have passed since you were a teenager. You have valuable life experience which will have at least some relevance to the subjects that you choose to study. I know that I am much better educated and informed now, at the age of 61, than I was when I entered university at the age of 18. Although even so, I have no plans to go back to university.