I don't think it's exactly completely delusional or obsessive to be sad that your dad is now financially unstable and obsessive about a single thing to the point it's alienated the people around them.
You can be well adjusted and sad that someone close to you is on a bad path.
You can even resent people you blame for enabling that path.
Are you going to tell me with a straight face you didn't tell them there was something wrong with them ("diagnose them")?
If your stated belief is real, then I'd encourage you to reflect on why you were willing to violate this principle, and why, after being challenged on it, you deflected.
TIt is common to dismiss someone discussing something they care about, on the grounds that they care about it; they created this account to talk about Musk, so we shouldn't be surprised that's what they're doing. They related something painful, so we shouldn't be surprised it upset them. None of this should be held against them or discredit them.
If you were in there shoes, and assuming everything they said was true - is there really a different way that you would have expressed it?