With 50K people infected, it's tiny slice of even the gay population.
But the threat that AIDS represents is much larger. Why spend a lot of resources fixing a tiny hole on a large boat? The hole isn't leaking much? Well, it's the scary potential that mandates treatment and prevention.
That's the number of new infections in 2006. As HIV/AIDS takes a long time to run its course, and it stays around for life with a very few exceptions involving bone marrow transplants from naturally immune people it, I'm certain that the total number of people infected is at least an order of magnitude higher. 500,000 people in the US is about one in 600, making it an uncommon but not especially rare disease.
But the threat that AIDS represents is much larger. Why spend a lot of resources fixing a tiny hole on a large boat? The hole isn't leaking much? Well, it's the scary potential that mandates treatment and prevention.