There are several reasons why I do brew my own beer. It is fun and you get to drink a lot of really good beer. Well, not everything is perfect, but there is a whole world of beer out there that one cannot really try unless you make it yourself.
Here in Norway, where I live, there isn't really much of a selection when it comes to good beer. The selection is decent, but you can drink your way through it in a few weeks time. Then what do you do? Well. Travel or stay home to make some yourself.
Norway is not a big country, about 4.5 million people live here, so the beer selection is never going to be huge. The decent beers that we do get here are for the most part bland Norwegian beers and a small number of imports. We do have a small number of microbreweries, Nøgne Ø and Haandbryggeriet being the best known ones as they are now being exported to several countries including Denmark and the US. The number of small breweries is increasing, but slowly.
Anyway, the main reason why I'm brewing I'd say is that I find it a very interesting hobby. It is a very creative process as a lot of brewing equipment and ingredients are involved. For each of the beers I brew I make my own recipes. This is half of the fun. Trying to pin down a certain beer style or a certain kind of profile is challenging, and you learn a lot from experimenting. After a while one is able to figure out how the ingredients work together and what it takes to achieve the right balance.
Learning is an important aspect of homebrewing. There is always something new to learn. There is always something you can read up on or experiment with. There is always some new kind of brew gear that you can build that make things more efficient, shortens the brewing process, increases flavour, or just looks cool. There is always some new ingredient you have been wanting to try out in a beer. You really never run out of ideas.
These are all, more or less, the same reasons why I work with computers.