Why is Elon Musk so afraid of artificial intelligence?

Elon Musk, along with a bevy of other smart people, have expressed concern over our experiments with artificial intelligence, particularly with the weaponization of sentient AI. So have these guys been watching too much Terminator, or is there a larger existential crisis we should be worried about? Woman transforms into 5 'Alice Through the Looking Glass' characters in one minute Notorious B.I.G. hit'Juicy' just got a vintage jazz makeover Guy achieves next level of love with Super Mario Bros. proposal