Selling them the elixir would be, in the words of Claude Maximilian Overton Transpire Dibbler, “Cutting my own throat”. In this case, they will do it for you.
Claude Maximilian Overton Transpire Dibbler is of course “Cut me own throat” Dibbler from Terry Pratchett’s “Disk World”. (Don’t try the sausage inna bun!).
Not really, It’s just keeping left of someone goes well back to at least the Middle Ages as it kept your sword arm free.