Your comment is making an erroneous assumption that all viruses are treated equally, when this couldn’t be further from the truth.

People are working hard on the finding a vaccine or other treatments for the HIV virus (and don’t forget we already have antiretrovirals and PrEP), and we are getting closer every day to a vaccine. There are many other diseases that are epidemic-scale that also do not yet have a cure (Alzheimer’s for example). HIV is an incredibly complex virus. Only ten years ago a friend of mine who is a biologist working in virology told me that a cure is impossible because of how it works, how it invades immune cells, how it mutates and how it can evade detection and lie dormant in ‘sleeper’ immune cells. However attitudes and forecasts have changed because biotech has come so far. Now the general feeling is that we will crack it, sooner or later.