It might be because even though it's a true story, it's so strange and out of the norm that he knows people won't believe it.
Even though he said "true story," I have my doubts. I think he's exhibiting signs of dementia.
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Bones: Robertson graduated from Yale Law School, I believe, and started a multi-million dollar organization including tv stations all over the world, relief aid, and a university. You might not agree with what he says (I don't) but it can hardly be argued that the man isn't "bright."
But he has been losing it over the past several years.