Criminology will teach you that there is a myriad of reasons people commit crime and committing various cyber attacks occur in similar fashion. Now the difference in rankings between why someone might commit a crime vs someone who would commit a cyber crime might be significantly different. The most relevant reason would of course be for the money, the same reason, if you are honest is why you are in the job or field you are in. The next two might be tied as they can often go hand in hand, Political reasons and Recognition. A hacktivist may want to maintain some amount of anonymity, but often the want people to know what they did and why they did it, who and what they represent. The next two after that may very well be tied, number four and five are Entertainment and Boredom. How better for someone to cure their boredom than to provide a little entertainment to the unsuspecting victim, whether it is to bully or to steal information or money matters not. There are many multiple other reasons, but I believe at the bottom of that list might be the Revenge factor. There may be the one or two who use the internet for their revenge, but they are likely the minority.