I'd say 99,9% are simply mentally and/or emotionally unstable people, caught up in their emotions, trying to let out the frustration onto someone they perceive as having the most fault. These people don't mean it - they're just feeding they're ego (perhaps perceiving themselves as dangerous when they dole out serious threats), trying to vent their frustration and can't control what they communicate to other people. If they were next to you when you angered them, you might get a punch in the face at most.
The remaining 0.1% are serious cases of sociopathy (psychopaths are usually much more manipulative and less impulsive; the likeliest death threat you'll receive from them is when one of them is standing behind you with a knife, slitting your throat). These people might actually try to kill you if you broke the news right in front of them. However, due to their impulsive nature, chances of one actually dedicating tons of time, trying to track you down, planning out the assault and then carrying out the deed (couple that with him/her being unable to locate you) is rather slim. Though there have been cases of attempted murder when someone was angered online, as far as I remember, most of those didn't involve the attacker exclaiming how he's going to decorate his Christmas tree with your entrails.
Looking at the other side of the situation, the people receiving those death threats (in this case the No Man's Sky devs) are somewhat well adjusted individuals, potentially with a more technical mindset (in this situation), which in turn causes them to perceive the threat as if a person like themselves sent it - that being actually real and dangerous. Stress and fear, despite their conscious mind trying to calm them down, builds up and to relieve it (and give the police a lead in the etremely rare case if it actually happenned) they post about it on social media.
This has been a psychology lesson by Not-Dr. 75 Off'ers (please research this crap; I don't guarantee any accuracy over the shards of psychology knowledge I picked up from the various places of the Internet).
P.S. They might have filed a police report AND posted about it on their social media, you never know. Then again, seems that the police are keeping such records in a "Investigate when reporter gets (nearly) murdered" folder, unless you're someone influential or well known.
you I hate you I'm gonna kill you" message without really thinking twice about it. I mean, I've gotten death threats just playing online multiplayer in certain games, but I've never thought twice about them nor been scared for my life.
