We all know what causes aids and how to stop it but some folks do not want to stop their aberrant, hedonistic behavior and no amount of "funding" is going to change that.
AIDS money funds the radical left sexual agenda and political action. It is a honey pot for leftists in the UN and the US. Funding research in the US at a reasonalbe level is one thing, but continuing to pour buckets of money into leftist social engineering is a disaster for the US.
In addition, we do not have the money to fund the world anymore; no one votes in the US for foreign entanglements and wealth transfer shake downs. It is a betrayal for our government officials to have such deep and lasting foreign entanglements and loyalities. With globalism, it has degenerated into disloyality to the American people and our country.
That being said, you are right -- in many cases it probably is a matter of gratification.
Maybe what they really need is not AIDS medicine, but cable TV . . . .