We all have unfinished projects. You know you do, so don't even pretend that you don't. Are you like me, and need to be working on multiple things at once? This is what leads to the ridiculousness of unfinished projects. Currently, I have 3-4 (I didn't really check) baby quilt tops, 2 finished lap-size quilt tops, as well as the blocks from 2 of my 3 virtual quilting bees. Don't even get me started on my unfinished knitting projects.
It's not that I lose interest, per se, but usually that I don't have supplies (so many quilt tops = no batting and/or backing fabric usually). I wish I could say that I have enough will power to not allow myself to buy any new fabric or start any new projects until all unfinished ones are done. Nope, never gonna happen.