There are many easy scholarships targeted at underrepresented minorities. So many you just need to apply to to get accepted. At worst pay someone $100 to write you an essay that will score you a $2000 scholarship.
There are also scholarship programs that just give you thousands of dollars for having a certain GPA and graduating from a certain school system. Not everyone just scoops up several thousands of dollars of private scholarships to pay their full cost of attendance. In fact most people don't regardless of race.
On top of that it's a requirement to list what other scholarships you get when applying for another. Scholarship foundations aren't going to give you another private scholarship if you got like 5 others when there are similar people with nothing applying for the same thing.
So even if it were possible to get minority scholarships it's only be a drop in the pool of other private scholarship funds that go untapped because people just don't know about them. Alternatively merit scholarships are likely given on a first-come-first-serve basis. It's ideal to go to a college that will pay for a lot of your cost of attendance rather than going to a school hoping that you can come up with tens of thousands of dollars in private scholarships alone.
consider the figures in this paper
http://www.finaid.org/scholarships/20110902racescholarships.pdfa small percentage of scholarships are race-specific, and require more than GPA/rank and take into account extracurriculars and community service (the things that actually get you into college/ get you scholarships over other people).
Like for example Achieve Atlanta is a scholarship that gives $5000 over 4 years of college to any graduate from an Atlanta Public School system school. The prerequisite for this is pretty easy (maybe like above a 3.0 on a 4.0 scale) and has no real restrictions based on financial need. I only had to go to some kind of event for it and now they've sent it to my school. The event had like 40 kids at it maximum (most black) which is ridiculous because the intention was to give it to so many grads. So if the majority of people wont get an easy and fully funded scholarship how could you expect one to find multiple private scholarships with limited funding? There's no reason to attribute my personal experience to how the scholarship practice works but it seemed so weird to me.