Why do people sign up and fill out the questionnaire (the multiple choice items) and never fill out the personal information? what shows on the left side of the screen?
Some people make an account just to browse the site and see whether they want to stay, so they fill out the minimum. Others are just lazy and never do it. Then they go on the forum crying about how no one will respond to their messages. Most women won't reply to those with blank profiles.
But no one can know for sure why people do what they do or don't do.