Some gay men, expose themselves to the virus if their partners have it in order to have sex without the need for protection and as a form of bonding.
However, some bug catchers enjoy 'collecting' STD's and will go out of their way to contract as many as possible. They usually enjoy telling people about thier diseases, are exhibitionist about them and see them as achivements. Some even cultivate or inflame the diseases, and do not seek medical attention in order to get disterbing symptoms or perminant disfiguration.
Normally, the more extreme Bug chasers or bug catchers care little for their well being are mentally disturbed and unstable. Most are sexually free and there may even be some that enjoy giving their 'gifts' to unaware sexual partners.