I use sunblock to do what sunblock's supposed to do because I am black and cannot afford to operate under the misguided assumption that having a quicker melanin response to the sun than people of lighter complexion means I am immune to its effects.
Growing up, no one ever said to me that I had any kind of immunity to the effects of the sun. However I do not recall any talk in the house about sunburn. I did not use sunblock as a child or and adult until a couple of years ago. What I did see, as a child, was others of my ethnicity not protecting themselves.
All that kind of gels together to form an attitude, a sort of tacit assumption of immunity. Although I have experienced sunburn, I have not always given much thought to skin problems from overexposure. It was after I started walking a lot that I started to actually purchase and use sunblock. Then a few months ago I saw a commercial about melanoma featuring African-Americans. And it is then that I made the connection.
Although it would require a bit of statistical research, I suspect that the number and most increases in cases of melanoma amongst dark complected people has to do with an assumption on our parts, however irrational, that we are immune to the sun's effects. We have lived our lives under a false sense of security for decades and now the cases are beginning to come to the forefront.
While the myth of immunity is not the sole cause of these cases I believe it is a strong contributing factor. Couple that with a shift in the climate, which has occurred over the last fifty years, inadequate nutrition, insufficient nutrition education, and you have a recipe for strong susceptibility.
Melanoma is, to some extent, what you might call a "gateway" form of cancer. It is not always detected and treated before it metastasizes to some other part of the body where it is detected later. It is possible that in some cases of diagnosis the patient never finds out about the melanoma, or that their disease began with it.
With all that said I would like to join the growing chorus of voices in recommending that all people do what is necessary to protect themselves from overexposure to sunlight. Your life could depend on it.