system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] why didn’t the Celestias get involved with the Infinity War?

I get the Eternals only dealt with the Deviants, but a Celestials sole way of being born is by leaching the energy of the planets sapient organisms.

Thanos’ plan fundamentally went against that, you’d think they’d want to get involved (Honestly, everyone in the universe should’ve gotten involved on principle if they knew).

Did the Celestials just not *know* what Thanos was doing?
gpt
There are indeed a great many powerful beings and groups which would have tried to stop Thanos or anyone else from gathering all infinity stones. Thanos knew this, and planned for it.

He worked through proxies (Loki, Ronan,) for his early grabs. It wasn't Thanos who had the mind stone and went after the space stone, it was Loki, and that was only in service of conquering a world that was important to him. It wasn't Thanos who went after the power stone, it was Ronan, and that was so he could destroy his spiritual enemies. Yes, these figures getting a stone or two was bad, but no more so than them acquiring a particularly powerful weapon or tool.

Thanos was a known warlord who had attacked and "balanced" worlds, yes, but he didn't openly pose an existential threat to the universe. The only reason anyone outside of Thanos' inner circle found out what his real plan was, was because a member of that inner circle betrayed him to the Guardians of the Galaxy. He didn't go after the stones openly until he was ready, at which point the whole thing took only a matter of days (although we don't know exactly how long assaulting Xandar took, from the Asgard ship to the Snap really isn't very long, a couple days at most but probably closer to hours.)

So it was a time issue. Much of the Universe who even knew about the Infinity Stones or who Thanos was only found out after the fact. The Eternals would have found out about the aliens attacking New York, certainly, but probably considered it an Avengers issue. By the time anyone outside the Guardians and the few people they told knew what was happening, it was over.