What is it about bikes?

I've been thinking about this lately and I wonder what it is about bikes that compels us to try to finish building up a bike that we know we won't be riding for at least a month? 
I've been working on the conversion of the Nitro niner into a single speed and ordered a Shimano Alfine chain tensioner that will allow me to create a 2x1.  I want to run a 44t and a 32 t chain ring with a 15t cog.  Conventional tensioners don't have enough range to account for the 12t difference and even though I have no intentions of riding the bike until at least march, I wanted it finished a week ago...
Just like I've been putting air into the front tire of my Gary Fisher even though I have no intentions of riding it until at least April...
So, any thoughts as to why we work so hard on bikes we have on intentions of using?