Vitamins are not a scam. But there are scammy vitamin companies. A lot of them.
Herbalife sold a good multi-vitamin, but the story of its start was completely made up.

The thing to know is that know one who had a good Vitamin D level ever went to ER for covaids.
Everyone who did had lower than average vitamin D levels.

The Cytokine storm, when seen in a hospital used to be stopped with a huge injection of vitamin D.
And, basically, if you have enough vitamin D in your system, you are immune to such.

And if we had healthy, nutritious food at the grocery store, and got outside in the sun with minimal exercise, we would have no need for vitamin supplements.