3. Jaws
The reason that the shark from the classic movie Jaws was allowed to kill so many people was down to the stupidity of Amity Island's mayor, the naivety of the beach-dwellers/tourists and the stubborn nature of a shark hunter. When a girl is killed and the death is confirmed as a shark attack, Police Chief Brody wishes to close the beaches until the shark is caught. However, he is over-ruled by mayor Larry Vaughan who sees the beach as a big money-spinner in the summer season. A shark is then caught, which is adjudged by aquatic expert Matt Hooper to not be the shark that had caused the deaths, but the mayor pig-headedly refuses to believe him and stupidly encourages people in to the sea, resulting in more attacks and deaths. Chief Brody, Hooper and a shark hunter named Quint then head out to kill the shark, but Brody realises it is too big so they must head back to the shore for reinforcements. Quint, however, wants the shark as a trophy and prevents this from happening, giving the shark more opportunity to attack - ultimately resulting in his own death. Essentially, the shark problem should have been nipped in to the bud much earlier, but the big fish was allowed to continue his human-eating rampage for way too long.