So for the past few days I’ve been hearing people talking about why Thanos is attacking the earth now. Many people are saying that he didn’t attack Earth sooner because at least one person of the three people viz. the Ancient One, Ego and Odin was alive and they’d have stopped him. So let’s breakdown the facts and get to what this theory has to say.
In Doctor Strange we saw the Ancient One saying, “The three Sanctums build a shield around the earth for protection against inter dimensional beings.” Thanos isn’t exactly an inter dimensional being. He’s a Godlike being that wants to wipe out half of the universe.
My point here is the Sanctums weren’t established to protect Earth from Thanos and other beings like him. No doubt the Ancient one is ridiculously powerful, but couldn’t have taken care of Thanos by herself or even with the help or Mordo and all of the Monks following her. Yeah she could have been a pretty good asset for fighting against him and his army if she were to join forces with other people like Odin or Ego, but here I think Thanos planning invasion on Earth just doesn’t has to do much with the death of the Ancient One.
Now coming down to Ego. We all saw in Guardians of the Galaxy: Vol 2 that Ego had planted something like a plant or a flower on the Earth and many other planets to spread himself and how he had planted his “stuff” in a female on each of these planets hoping for at least one offspring that would carry a connection to The Light like he did. So if Thanos were to attack Earth for the Infinity Stones Ego would definitely have stopped him and let’s be honest here, Ego was a pretty basass character in the MCU and still is in the comic book world. He would have definitely put up a fight against Thanos and you never know, even would have won it.
In the MCU Ego is a Celestial (although in the comic books he’s not). Celestials are one of the very few most powerful beings in all of the Universe. But the main question is, did Thanos know that if he attacks earth Ego would attack him? Did Thanos have any idea about Ego and his plans? According to what we’ve seen in the movies so far, no one else knew about Ego’s plan except for Ego. So the presence of Ego wouldn’t have affected Thanos’s invasion on Earth. So yeah, there’s your answer. Thanos not attacking Earth yet has probably nothing to do with Ego.
Now our final character, the Alfather Odin. This guy is interesting. Odin was the king of Asgard before in died in Thor: Ragnarok and the God of wisdom, poetry, war, death, divination and magic. So he’s pretty much the combination of all the Gods in Norse mythology. Being the king of Asgard, it was Odin’s responsibility to look after all the nine realms (most importantly Asgard and Midgard i.e. Earth) and keep huge threats like Thanos under check. He’s one of the most powerful beings in the Universe and has Odin force at his disposal for use against huge threats.
According to me, Odin put a spell on Earth for its protection against Thanos and others like him using his immensely strong magic and the Odin force. The spell was protecting Asgard and Earth for very long time but went off after he died in Thor: Ragnarok. We saw in the movie that Hela too was under a spell from Odin that restrained her from coming back to Asgard and she came back soon after Odin died. Meaning that the spell was lifted soon after Odin passed away. So same might be the case with Thanos. That’s why Thanos appearing at the end of Ragnarok along with the Black Order and his army makes sense. So in my opinion it was actually Odin, Thanos was waiting to die for.