Money would be the main reason. If you're a teen and money isn't really required at the moment then it is safe to just quit and not worry about it. However I usually only hear this said to adults who have bills to pay. Last thing you would want is to quit your job and not be able to find another one which would result in bills backing up and going unpaid.
UnknownFoxAlpha t1_ja8kir6 wrote
Reply to ELI5: Why do people give the advice that you shouldn't quit your job without another one lined up? by tradice9
Money would be the main reason. If you're a teen and money isn't really required at the moment then it is safe to just quit and not worry about it. However I usually only hear this said to adults who have bills to pay. Last thing you would want is to quit your job and not be able to find another one which would result in bills backing up and going unpaid.