system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] In Endgame, after Thanos punches Captain Marvel with the power stone, why doesn't he slam his fist with it in the ground and destroy the earth?

Like how the celestials destroyed planets using the power stone. Is it because he needs a weapon to store the infinity stone to use it or because it would kill him in the process and not allowing him to wipe the slate clean for the universe?
gpt
This Thanos has only just acquired the power stone for the first time.  He isn't used to using it, but he is used to fighting with fists and blades.  His mind likely went with what it was used to rather than with optimal choices.  He may also have been holding onto the mindset of a battlefield commander who wanted to preserve his forces rather than as a pseudo-god who could remake his forces at will.

In general, Thanos does not seem to gain anything like a 'cosmic awareness' with the stones that would let him know the precise best choices to make.