Nope, a scam has to be of benefit to someone. Who would benefit from that belief? Oh, the drug companies...OK, maybe. But my point is that if you don't (or someone else doesn't) do the behavior you will not be afflicted. The "someone else" would be the infected homosexual or IV drug user who donates blood. Not your fault if you get it that way, but still spread by a BEHAVIOR.
You are correct about the behavior. The behavior, unprotected anal sex with multiple partners, essentially guarantees you will get infected with something on a continuous basis. Let’s call that something AIDS. You don’t need an HIV virus to predict that outcome.
The “beneficiaries” you are looking for are the members of the gay community. They like their behavior. They want to keep it. So tell them HIV is the real problem and then spend decades and billions of mostly tax payer dollars looking for a cure. It hasn’t been found. It will never be found.
If you want to do a little research go hunt down the definitive clinical study or studies that prove HIV is the cause of AIDS. You will be surprised to learn that you can’t find it. There never was a definitive study. Never was. Never will be.