Who is the richest man on planet?

I don't get how people know enough information but themselves don't know it!

A video said Arnalt is "richest man on planet" due to $240 billion, worth while listing mars family $250 bn. Why would someone who know both call 240 "richest"?

Similarly the writers of star trek discovery wrote: the federation captain not knowing about the klingon battle in her generation, but writers also knew about it, to write the klingon character mention it. Why would they do that? Knowing the detail but not knowing it?

Who is the richest man on planet?
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