Why Do Web Developers Neglect Their Own Sites?

In the last six months or so, I’ve noticed a rather disturbing trend amongst Web developers and designers: We seem to neglect our own Web sites. There are so many sites for Web developers and designers that go months (even years) without any changes or updates. I won’t link to any in particular, as I don’t want to call anyone out. But it seems to happen fairly universally; moreso among those of us that do design and development as a side business, while working full-time jobs. I know I’ve noticed no less than 10 other Web sites that suffer from the same problem over the last few months.