system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel Universe] How is Thanos "powerful"?

I was just watching Guardians of the Galaxy, and it said that only "powerful" beings could control an infinity stone. Then they said that Thanos could handle it because he was the most powerful being in the universe. I guess he's physically large, but what exactly does "powerful" mean in this sense?

Edit: I guess the big question I'm trying to get at is what properties it takes to control an Infinity Stone.
gpt
He's a Titan, an offshoot of humans created through the genetic tampering of the Celestials (the race that left thqt giant head that became Nowhere) and are basically Mutants on steroids without the control issues, given the Super Soldier Serum, and with tech that makes the Xandar and Kree look like stone-age savages. 

He's 'Powerful' out of a combination of biological superiority, technological superiority, intellectual superiority, and a ruthlessness that would see him destroy the universe for a date.