I know someone who posted that her relatives kept a previous war from taking a country and is worried about family there, right when the Ukraine war began, with no mention of either country. People assumed she was talking about Ukraine and poured all kinds of prayers out – for her. At some point she commented it was a different country and all her relatives are there living on the border of Russia. But she has relatives in the US and other countries – not “all” there. Plus, none of the relatives live on the border – none. She wanted people to sympathize with her – but instead of correcting the post to explain it wasn’t Ukraine, she left it in the comments - and most people don’t scroll through the comments. Thus, many more shocked people commented more, assuming all relatives are in Ukraine, offering prayers to her relatives elsewhere and not for the Ukrainians. She had to make it about herself, to get sympathy directed toward her. Her ego has no checks.
Others (who make it about themselves) offer their take on a situation from knowing someone who had a similar experience – inserting themselves directly into the narrative, making it about them instead. Occasionally, it can be informative, but usually not, as no path or lesson can be derived from it – just more focus on the person talking. Many times, the situation he describes doesn’t even relate well to the one in the original discussion – just a sidebar that derails the topic.
It is annoying that people are so hungry for attention (or so full of ego) that they make every situation about them or discount other people's stories. We can counter them with facts, but they will likely ignore us and maintain the farce.
Depending on how well you know the person, you can try to rein him in. You can refuse to talk about the subject and change the subject. For your mood, just try to ignore it. This is the age of “alternate facts,” so it is hard to fight for the truths. It rarely changes anyone’s minds – no matter the proof that is shown.