Why there is people who like to make other's life difficult??

There is so many different type of peoples in this world, and one of the kind that i hate most are those who like to make other people's life difficult.
Especially those who have authority, they can simply request to cancel your meeting at last minute, or asking you to change the meeting time few minutes prior to your meeting, or simply change the approval decision-----all this make the life of the execution people miserable.
I hope one day those people will kena and learnt their lesson, then improve themselves :)