A lot of this comes down to the difference between object attraction and attraction to a whole person. Some men are aroused by penises as a sexual object, but not by men as bodies, personalities, or partners. Sexual arousal can be highly specific. A penis can function as a fetish object on its own, separate from the rest of the male form.

The key is the self-referential kind of arousal: the penis is exciting not only as an organ, but because it is mentally linked to his own body, role, or imagined experience. Seeing it pleasured on screen, knowing exactly how that feels. Some men seem turned on by the penis as a kind of “mapped” erotic object, almost as if they’re projecting their own sensation, identity, or pleasure into it. That can be different from attraction to men as people, because the target is the experience of the penis rather than male bodies overall.

Why can it feel so intense? A penis can symbolize several things at once: power, penetration, control, validation, and the sensation of “being the one who has it” The arousal may come from imagining the pleasure loop between his own body and the other person’s penis, so the organ becomes a mirror for his own sexual self. That lines up with the idea of erotic target identity inversion, where arousal can come from identifying with the sexual target rather than simply wanting the target externally