[boyband6666]

Except for the fact that it's expensive to keep people on HIV meds, thus increasing the value of a cure. And the meds are made by lots of companies in competition - if anyone had science they thought would lead to a cure, they would be all over that straight away.

This also assumes that the only motivation is money, if a researcher came up with a cure for HIV they would become an instantaneous scientific god, immortalised in writing, films, having streets and libraries named after them. They would be a hero. That motivation is pretty powerful for many (not for all of those things, but the be a hero part).