Why do people change jobs?

• For a better pay
• For job security

The above two works together and it is hard for someone to choose, especially when loyalty is not attached. Jump to a higher paying campaign that might end next month or remain in your present campaign that may stay till next year.
Others reasons include;

• Number of posts required to be made
• Permitted areas to make post
• The leniency or strictness of the campaign manager
• The promptness of pay 

Among others.