Um that 8 folf star is the symbol of chaos from Moorcock's work. 40k appropriated it, in Moorcock's stories chaos and law are balancing forces. It also saw extensive use in occult stuff before warhammer.
My understanding of why it's popular as a symbol in like Greece, Chili etc is in the Moorcock sense. I.e. when states centralise and suffocate chaos is needed to restore freedom and balance. Similar to flying a black flag as the negation of flags.
Nothing in 40k is original and everything in it is a shallow ripoff of something more interesting.