If this movie is such a flop at the box office how could it possibly pick up seven nominations for a Golden Globe?
Ordinary moviegoers find its theme repulsive. The Hollywood congniscenti are not ordinary moviergoers.
It is the "best" movie only if you have a warped view of what qualifies as quality entertainment. Brokeback Mountain is a movie Hollywood made for itself. The storyline perfectly reflects Hollywood's liberal conceit and morally dissolute values. That's why the Hollywood congniscenti rave over it.
Brokeback Mountain might even win the Oscar for best picture. It is analogous to nominating multiple murderer Tookie Williams for the Nobel Peace Prize, or awarding it to the dictator-appeasing Jimmy Carter or master terrorist Yassir Arafat--two men who have done more to undermine world peace than any other two men in the past 35 years. But they satisfy the warped Nobel Committee's liberal sensibilities, so there you have it.
Because the Golden Globes represent how much critics WANT a movie to succeed, not necessarily how good it is. True, there occasionally is some correlation between those two factors: it's normal to want a movie you've liked to succeed. But they are not the same thing.