My explanation for that is not the fundamental lack of interest in the project, but the hidden fear of failure that accompanies every project that I work on.
I've worked on so many failed projects that I've kind of lost hope of actually producing something that won't be forgotten immediately.
(Mind that this is not necessarily true - some of my work (as a comedian/writer/actor) has been viewed millions of times, while some of the code I've written is being executed by millions of machines every day, but I still feel like I've failed at everything, because that was just "blind luck" ).
If all this effort results in disappointment and depression, why bother waste energy on it now - this is the kind of hidden thought process that's going on in my head and I guess in many other's people's heads too.
Paradoxically, this is the thought process that also disarms you a little bit every day, until the task becomes painful and not worth pursuing and once again you've failed to accomplished what you've set out to.
It's a self-fulfilling prophecy, but also hard to break since it's not happening on a "rational" level, but on a lower "fight or flight" subconscious level, which is very hard to control.
It's so easy to wind up with an infinite list of chores. Continually pushing a lot of them off as late as possible works rather well, in my experience.
1) Finding a better solution and 2) Finding out you didn't need to do it at all are two great outcomes from procrastinating.
Short version: People sometimes use commitment devices (like Beeminder!). Doing so is an action and the preference it reveals is that the person engages in actions contrary to their own preferences!