++++ The Vancouver Study says 8 to 20 years less than you or me. There seems to be very little other data on this subject. The Gay Community is in denial on the subject and political pressure is clearly against performing some real science and publishing the results.
The question conflates multiple risk categories, because not all homosexuals engage in risky behavior. Even with current treatments, a 35 year old with HIV might be expected to live about 20 years less than a healthy 35 year old. At age 65 the decrease in life expectance might be much less, maybe 5 years as a guess.
It's an interesting question, but I don't think there is any good answer. The Vancouver study was of "a large Canadian urban centre from 1987 to 1992". The problem with using that as the basis is that HIV treatment was not as effective 20+ years ago as it is today. Since the American Psychiatric Association decreed that homosexuality was not a mental illness in 1974, it's probably about as difficult to get gov't funding to study this issue as it is to get gov't funding to disprove Anthropogenic Global Warming. I came across one study that concluded that there is no difference in life expectancy in male homosexuals (I don't believe that this is even remotely possible) but that lesbians had a shorter life expectancy because their suicide rate was higher.
For the record I am one of the HIV causes AIDS deniers. The idea that one single retrovirus is the sole cause of the destruction of the immune system that leads to AIDS related death is simply absurd.
The at risk gays are those who engage in anal sex with 50 or 100 partners while consuming immune suppressing drugs. These are the ones who are going to have a shorted lifespan. Multiple repeated infections, overuse of antibiotics and anti-viral medications would do any of us in. We know this happens. Why we blame HIV for it is beyond me.
What percent of the Gay Community is this group? I think it is pretty large but I really don’t know.
But the real mystery is: why don’t we have better data?
And the answer is (I’m betting): the Gay Community doesn’t want to know the truth.