At the end of the day, a good chunk of the plot in Doctor Strange centers around a particularly controversial decision made by The Ancient One (Tilda Swinton).
Looking at the scenario from The Ancient One’s perspective, it’s definitely a complicated matter — but according to Tilda Swinton, there is very good reason why the morality question within it is left open-ended.
It’s this decision that not only leads Kaecilius (Mads Mikkelsen) and his fellow zealots to revolt, but it also has a big hand in Karl Mordo (Chiwetel Ejiofor) leaving Kamar-Taj.
While she spent decades, if not centuries, telling her students/followers not to mess with the powers of the Dark Dimension and the dread Dormammu, she herself was using energy from the timeless realm to basically become immortal.