In my personal experience, the guys who go around constantly threatening others are full of hot air, particularly inside their cranium, as they are seemingly oblivious to the very concept that they're placing themselves in danger by running their mouths off like that.
Seriously, there are no shortage of ways for folks who go around threatening others all the time to get into trouble, drawing attention to themselves from all sides, putting everyone on edge, it's bound to go badly for them somehow, someday. They could threaten the wrong guy, be it a good guy who simply takes the threats seriously, or a bad guy who simply responds to threats with violence regardless, they could even end up arrested and imprisoned for a crime they didn't even commit just because someone they were harassing ended up getting murdered by someone else but they took their threats too far, that someone else overheard them, and did exactly as the threats were described to throw suspicion on the one who made them. But a fool would never consider any of the possibilities, they just run their mouths, thinking they can say whatever they like without any consequences, and when something inevitably happens as a result, nobody cares because its awfully hard to make any friends acting that way, or even remaining neutral enough for someone to stand up for them on principle.