In the tropics lives a huge portion of the human population but I am not aware of large incidences of melanoma there, melanoma incidence is large in places like Australia where most people don't live in the tropic but most are of pale complexion and live right under the ozone hole.
I am not suggesting everybody should live in the tropics and I am not suggesting it would be an healthy choice for everybody, the fair skinned individual probably does better at different latitudes, of course.
If one doesn't have a pathology where supplements are the therapy or doesn't have very special needs like athletic performance healthy nutrition and lifestyle should rule out the need for most if not all supplements.
If we state that tossing a supplement is easier for most than having a sound nutrition and lifestyle I may agree but if it will suffice in order to achieve the same results I am not so sure.
A different topic altogether is if the goal is life extension, given a perfect nutrition and lifestyle some kind of supplements (likely not yet discovered or at least proved to really work) might be necessary, but that is a specific goal and chances are they will be called "drugs", not "supplements".
Do I need supplements to go training at the gym?
No.
Will supplements help me to achieve better results?
Maybe, it largely depends.
Do I need supplements in order to compete at the Mr Olympia?
No, you need steroids (and lots of them).