I was trying to come up with a username back in 2015 and "hivfag" came to my mind, I believe it was because me and my friends joked about the existence of Super AIDS at that time.

The "fag" has nothing to do with homosexuals, it was instead inspired by people calling others "animefag" and stuff.

And it kinda suits me because I thing HIV/AIDS is a very interesting disease.

And more importantly I find it funny.