Here is some more information from this study about millennials. It states that a major reason is to have a place to call home. They want the comfort and security that their own home provides.
When you are a homeowner, you control who comes into your home and you can decide how to make it as secure as you see fit to do.
They also want to live in a nicer home. They also want to be able to accommodate their growing family and make the changes to the home they feel are necessary or desired
Many have also responded that they like the idea of being engaged in their community. And another reason that they have decided to buy is to provide Financial Security for their future.