That is the best reason why. Video games by design are sold along side of other media. Media is pure entertainment. From the movies to musics. Video games in today's age have both in them. Plus many other aspects. When I was a little kid I used to go to the mall and spend a roll of quarters at my local arcade. Over time as technology grew and newer designs came about. Consoles were released and the gaming era took off. Individual game sales shot threw the roof along with the price of the materials also.
To many times have I seen commercials that aim around how robust the graphics are on the new titles. Even over time the requirements of games have skyrocketed. It used to be only a few pixels that made up a game, now you need powerful 3d engines to run the graphics of the games. Along side that you computer or console needs to be up to par to run the game. Not to mention all of the different types of graphics.
Games are so fundamental these days. Seems like they have a game out for almost anything. With new technology emerging every day with toys like the wii which adds tons of body interaction. It really helps to put you into the game.
4. Multiple Player Functions
Your sitting around playing you favorite game. Now imagine that with also playing with thousands of other players around the world. It lets you compare how well you fair against them. Some having top ladders and different modes of play.
Some people just like a good challenge. Games are designed to be challenging as to give off a replay value. Playing games with multi player adds a great deal of challenge as it not only challenges you but also other players to be the best. Who doesn't want to be the best?
Writers work hard to create a storyline for games. When games first came out there wasn't a need for a story line. The game just did what it did. Today game have immerse story lines that can go into several cds long. World of Warcraft has made two expansions to the main game that started their craze. All which made amazing sales. It stayed alive because they came up with a nice story line and the game had amazing depth.
7. Character Development
Some games such as the bigger named World of Warcraft has a nice player creation's system and along with it the way a character progresses in the game. Gaining levels, attaining new skills, collecting items and PvP which is a big deal in some levels.
8. A Home Away From Home
Some people play games to escape their own reality. All for their own reasons. Games today have to put warning labels on them. Poeple will play the game so much that they forget about their real life. Kinda wierd if you ask me but hey thats life.