1 - It wants you to verify whether the story is fake or not, because if it is, sharing it will help spread it further, which may have negative consequences.
2 - Because it may contain some truth in contrast to fake news, which are 100% made up.
3 - They're trying to convince other people to their (usually) political views (influence their opinions).
4 - Because hate hoaxes can blame other people.
5 - Simply to get a reaction from the Internet users.
