Feng Shui... not the movie

Here's the gist, why the heck is there feng shui? and what is it all about? as an architect, I've had experiences with people who have a deep belief in these things, and sometimes it just perplexes me how they do...
Now I'm no expert in analyzing things, and I hope you correct me if I'm wrong but I think the main concept of Feng Shui is to attain luck, as much of it as possible, why? I have my ideas but I'll get to it some other time... tell me what you think first :D