Musk just has a weird mouth feel (has the same strange feeling like saying "Moist", to me), Elon just flows of the tongue better, (both literally and metaphorically in the "thought voice" sense), and also is rather unique (unlike Jack, Tim, Mark or Jeff, Elon is a far less common name)

if it gets the point across, why quibble over such minor details?

Also, on a seperate point, Elon has rather created that familiarity by his constant Twitter updates, we FAR more about Elon, both personally and professionally, on a MUCH more regular basis, than like the next thousand billionaires combined. It's not strange that people DO genuinely believe they are acquainted with him in some way.