Getting scammed is the at the least concerning end of the deep fake scale. It could be used to start a civil or world war by creating footage of an attack that didn't happen which therefore rationalizes some retaliatory response. It could be used to frame people for crimes, especially inconvenient people who disagree in public with someone very powerful. It could be used to eliminate entire cities by creating footage of some kind of plague, something like the "Outbreak" movie, which requires bombing the city out of existence for the greater good. These scenarios are probably mild compared to what some evil genius could conjure.
