Well, even though I've actually got a pilot's licence, I have also got a full airliner cockpit halfway constructed in a spare room, and I'll tell you why:
It's a challenge to build it and I enjoy doing that, working out how to build the controls and such. I'm in no rush to complete it though (and yes my wife hates it), it's just a fun thing to mess around with whenever the mood takes me. I can go and fly the real thing when I like, but it doesn't stop me building the thing, as it's more like 'building a convincing movie set' that I find the fun part.
Chock