First of all the analogy fails in the real world. The vitamin market is huge. People pay lots of money to buy vitamins.
Second, the transition is not clear. It’s hard to draw a line line and say now this vitamin turned into a painkiller.
Third, I believe almost no product is a real painkiller. We in the West at least live in sheer abundance. Almost none of our problems is really painful. For example: was Facebook a painkiller? Hardly. Was the iPhone a painkiller? Not until you considered using it.
I’m not saying the analogy is useless. But I don’t think that vitamins can’t be super successful.