The Washington Post's Outlook section has an article Five myths about the Dream generation that gives you a good picture about who is affected. I heard about the DREAM act not from the press or social media but from a friend. He is a legal immigrant and has applied for his green card. An application is never a guarantee for approval and the green card process in the US is long and involves several years of waiting. His kids are in high school and looking forward to college. His options are:
a) Assume the best about his green card application and put his kids in college here and live happily ever after.
b) For whatever reason the green card application gets rejected and then his kids who will be in college will lose their legal status and have to leave college a risk any parent may hesitate to take
c) Choose to migrate to Canada where he can get permanent residency and citizenship if they live for 3 years in Canada
If the DREAM Act has been passed, even if his green card application was not successful, his children would have been able to stay on and complete college in the US.