As said above.
I only game for the social aspect, especially when hanging about on online games :D

I frankly have no idea

Entertainment. Sometimes I play non thinking games that make me run them on automatic, other times I want to think, figure things out and feel immersed. Sometimes I want to play a story and want to know what happens next, other times I just want to run around in circles, most likely killing things and keeping count.
Gaming is quite the stress reliever, except when you're stuck in some stage you end up playing over and over again. The fact I'm accomplishing (pointless) things entertains me far better than sitting on the couch flipping channels or avoiding to fall asleep while reading a not so interesting book.

Motivation...? :)
Well, to have fun. To experience some good stories. To escape from everyday's real life issues a little (WoW helps here a lot :p).

Gaming is one of a number of ways I relax and have some fun. Sometimes I feel like reading a book, or listening to music, or playing guitar, or watching a movie, or playing board games with the kids, or... gaming is just one of many ways to enjoy my free time.

This.

A good game is like a film, a book and music album all in one.
The perfect escapism.

I don't know.

Escapism
Better then drugs, drinking, and sex combined. Well maybe not sex but it's close.
Like I tell people who I sell them to it's an addiction but better then most.

To repress my instinct to kill :-P

Fun...
What other motivation do you need?

'cause it's fun.

Escaping form reality's boredom, to have some place when I can freely unleash the beast without hurting anyone, to get some inspiration.

I play to waste time, and to escape from reality. It's a very undemanding pastime, except in terms of money.

I find gaming is something is something that you don't really want to stop doing.
Good way to relieve stress, too.

That really depends on what games you spend your money. If you wait and take weekend offers, you end up spending less than 6-10 dollars per game. Compared to what you'd spend going to the movies or doing something else with the time you spend getting yourself entertained (2 hours for a movie, several days for a game) it can be a decent hobby money wise.
If you only buy the latest games and breeze through them in one sitting, then yes, it can get expensive.