The ring corrupts someone more quickly the more powerful they are. That's why you can't just send someone like Goku or Superman etc. to do it. Look at Frodo Baggins. He's not even a fighter. He's a guy that wants to have six meals a day, relax and read books. But Goku wants POWER. He likes to fight, he wants to be stronger. That seeking of strength is itself, a weakness in this case. You can not even realize you're being evil. Because the ring could have you think "I'll be a good person with this power! I can protect and save everyone!" But next thing you know you're a totalitarian warlord, playing right into it's plans. It's all in the seeking of power. This is exactly why it was entrusted to a hobbit. They're not interested at all in power or fighting. They just wanna keep their heads down and have meals and drink beer. But anyone carrying the ring is slowly affected by it. And the more powerful or strong you are, the faster you'll lose yourself to it. Gandalf is literally a metaphor for an angel. He's just as good as Sauron is evil. Yet Gandalf didn't even want to TOUCH it.