For me it is a combination of factors.
There is an element of self sufficiency. You're making something to make your life better in some way. Look at my avatar, couldn't find carriage lamps for the garage that weren't made in China, so I made my own, note the scroll sawed flower from copper.
I was a estimating manager in printing, woodworking is a opportunity to work with my hands as well as my head.
There is the endless variety and beauty of wood.
When working with wooden objects there is an opportunity to be creative, or if you're not, you can just follow plans from a magazine or fellow woodworkers.
It's fun to make items for family members and friends. Often these are items that will be cherished.
It is a hobby that you can grow with, as you develop your skills. What's more exciting than personal growth. Look at projects you did a couple years ago and the one's you are working on now. That's growth.
And you can turn your hobby into a business if you are feeling ambitious.
Last, but not least, you get to meet and share ideas with the nicest people like at SSV.