If you think you have a deficiency, explain why to a doctor. A blood test to know for sure is simple. A doctor will know what kind of supplementation would best serve you, and there may be an underlying reason that can be treated to fix it.

I didn't say "no one should take supplements ever," I said most people who take supplements are doing so unnecessarily, and you should do so under the supervision of a physician.

You may have a specific deficiency, but your story does not constitute data.

There have been many studies that have addressed this specific issue. Literally billions of dollars are wasted every year on these supplements. If you have a healthy diet, you are very unlikely to need supplementation.

This is the availability bias, because your experience is normal for you, you unconsciously think your experience is more normal than it is.