I probably get three times as many clicks from YA as from HP. If you continue to answer more questions relevant to your hubs (and leave your profile or hub page as a signature), when someone searches for an answer and opens up the YA page, they will find your address/link. Thus, you may only have a few clicks from that answer, that day, but many more as time progresses.
The other reason? I enjoy helping people by providing the information I have learned.