Yes you are right, the effect is limited: you die. That's true of every black swan - the worst that can happen is everybody dies. But I don't think that anybody would consider that a "mediocre" outcome. And at the end, you could/should quantify it in your model, or at least mention it as an unknown in your ROI.

You do not mention any studies of long term effects and you consider FUD raising the possibility that there could be adverse effects. When more and more studies show negative long term effect of substances that were considered innocuous (like vitamins), it's not FUD, it's being reasonably cautious.