It can be difficult to grasp how long fifty years are without context. So when you hear that the number gets filed away as "a long time" which isn't helpful at all if you've also filed away a millennium as "a long time". Being told a styrofoam cup takes fifty years to decompose is easily forgettable. Being told that a styrofoam cup takes the lifetime of an African elephant to decompose is a fun little bit of trivia.