These kind of people are nuts. I want to be one of them.
Sure, we spend 1-2k on an arcade cabinet, and spend about 1-2 months of time on it. But thats portable, and not really that big of a thing when all is said and done.
But then people like this spend 20-50k on a movie theater, and takes them many months/years to complete. I could never build one myself, but boy do I want one! (need a house first... i think)