[guardiangod]

Because the paranoia will worsen, and one day he will accuse you (or your siblings/wife/his siblings) of doing harms to him, even though it's pure paranoia.

Examples include trying to steal assets from him, belittled him with offhanded comments, or betrayed him even though he helped you in some distant past.

>In a way, that's actually kind of an admirable attitude, it's only sad in this case because he's so wildly wrong about what the truth is.

I totally agree. It is indeed admirable that someone can be so convicted in his beliefs. There is a certain beauty in that.

[Ajedi32]

The situation described in the article isn't schizophrenia or bipolar disorder; or at least it doesn't seem to be. His father just started believing online conspiracy theories

[bell-cot]

True. It would be wonderful if the decades of gradual-but-major mental changes in his father somehow stopped progressing...