Cal Hampton is Jason's mate — a small-time associate who has fully opted out of ambition and is perfectly fine with that.
While the rest of GTA 6's cast is chasing money, freedom, or power across the state of Leonida, Cal has found his comfort zone and settled deep into it. He hangs at home, cracks open a few beers, monitors Coast Guard radio frequencies he has no business listening to, and keeps a few private browser tabs open that you probably don't want to know about. That's his life. That's the plan.
Rockstar describes him as being "at the low tide of America" — and crucially, he's happy there. Cal isn't tragic. He isn't desperate. He's just a guy who has looked at the world, decided the psychopaths are in charge, and chosen to watch the chaos from a safe distance rather than wade into it. His personal philosophy seems to be something close to: if everything on the internet might be true, why go outside at all?
He's connected to two people who matter. One is Jason, who is clearly cut from different cloth — someone with bigger plans and the drive to chase them. The other is Brian, a mutual associate that both Cal and Jason are linked to. The details of that arrangement are still unclear, but it's worth keeping Brian's name in your head.
The reason Cal matters to you as a player is this: every good crime story needs someone who represents the road not taken. Cal is the guy who knows enough to be dangerous but wants none of the consequences. When Jason is out there doing whatever Jason does, Cal is the contrast — the version of this life where you stay low, stay paranoid, and stay alive. Whether that's wisdom or cowardice probably depends on how the story goes.
In a state where everyone is working an angle, Cal Hampton's angle is simply not having one — and that might make him the smartest person in the room.