The two principles that explain most of gay deviance are their Peter Pan-ism and having the minds of addicts. Little children are interested in ancient civilizations, and fascinated by the future, so the Peter Pan tendencies of gays does not tell us why they are uninterested in the non-present.
Rather, this seems to be due more to their addictive mind -- only out cruising for this moment's fix, whether scoring drugs, sucking cock, shopping, or getting showered with attention from their fag hag friends. Earlier fixes don't matter once their effect has worn off, and fixes too far into the future won't give them a rush right now.
What's the evidence for their not caring about the past or future? Lots, but just to throw out a few examples:
They've never been big in the environmentalist or other preservationist movements, which are usually manned by upper-middle class European do-gooder types. They don't contribute to futuristic fiction, whether in its nerdier or dreading genres. Not to mention how heavily they discount the future by ignoring how decrepit they will become so quickly because of AIDS and the thousands of other diseases they'll pick up, just to indulge their kinky sex lives.
Gays also have no sense of their own past, even the recent past and even when it was political and confrontational, similar in tone and spirit to the racial-ethnic civil rights movements. No fag under 30 or so knows what ACT UP was, and probably wouldn't be able to say much about the Stonewall Riots. They did make a homophile movie about Harvey Milk, though, so they may know about him.
I know there's a stereotype that gays are the preservers of old show tunes, but I don't see that. It may have been true for some small cohort of queers, but today's younger gays couldn't even tell you who the gay singers from the 1980s were, and they were very popular. They are just too caught on the fashion treadmill to wander back in time -- anything earlier than Lady Gaga, Pink, and Katy Perry are all kind of a blur to them.
This shows just how little sense of collective memory they have, as none of their favorite singers today -- or anyone's favorites -- are actually gay. Fag hags maybe, but not gays. As recently as the '80s there was Boy George, Rob Halford, Freddie Mercury, Pete Burns, Marc Almond, Neil Tennant, George Michael, Michael Stipe, just to name a few. In fact, I rarely see gays at '80s night compared to a random night out at a club -- one of the great things about it -- even though you'd think that music would be right up their alley, not just for danceability but also starring more of their own.