you don't have a great mental toolkit for teaching you about logic, but let me try and teach you. Just because alcohol doesn't always give you cirrhosis, doesn't mean that it doesn't cause cirrhosis. Just because cigarettes don't always give you lung cancer, doesn't mean they don't cause lung cancer.
yes there is a debate about the benefits of sunlight - but it is still true that sunburn causes melanoma.
science is constantly revising its opinions - but surely that's better than being dogmatic which seems to be what you're advocating.