Someone on mind-altering drugs and/or schizophrenic.
B-I-N-G-O - paranoid schizophrenics go from being manageable/seemingly safe to committing murder and mayhem in a flash. That is why being around them is so risky. In a second, they come to believe that people are conspiring against them and must be killed. And you never know when that turning point will be reached.
Oftentimes, the mental illness and addiction mask each other. Typically, an addict/alcoholic never gets sober enough for there to be a clear diagnosis of the mental illness aspect. If there is a commitment to rehab that last long enough, the problem can be decomposed.
It’s a mess to be sure, and a tragedy for the family.
I must say that I do appreciate DJT’s comments. At first, I thought he shouldn’t have addressed it - but then, if you let people get away with delusions and deliberate untruths just because they are familiar and have easy media access, that’s not right. Reiner said and supported a lot of polemical political messaging that he must have known was not true. That lack of integrity is not mitigated by a tragic death.