We know Frodo failed at the last moment to destroy the One Ring.
If he had been able to keep it would he have become some ubermensch or would he be in thrall to Sauron or would he die (he seemed at the end of his rope when in Mt. Doom)?
More broadly, would possessing the One Ring make anyone super powerful? Obviously, Golum was not powerful although he had long life from it. Galadriel had a moment where she resisted the thought of the power she would have. Gandalf was very cautious with it.
So, if Susan from Nowhereville got the One Ring would she rule the world? Drop dead? Or become some zombie thrall to Sauron? (e.g. a Ring Wraith but maybe more?)
Elrond explained it pretty thoroughly in Fellowship:
“We cannot use the Ruling Ring. That we now know too well. It belongs to Sauron and was made by him alone, and is altogether evil. Its strength, Boromir, is too great for anyone to wield at will, save only those who have already a great power of their own. But for them it holds an even deadlier peril. The very desire of it corrupts the heart. Consider Saruman. If any of the Wise should wield this Ring to overthrow the Lord of Mordor, using his own arts, he would set himself on Sauron’s throne, and yet another Dark Lord would appear. And that is another reason why the Ring should be destroyed: as long as it is in the world it will be a danger even to the Wise. For nothing is evil in the beginning. Even Sauron was not so. I fear to take the Ring to hide it. I will not take the Ring to wield it.”
Importantly, the hobbits don’t have “a great power all their own,” aside from surprising resilience. That’s the whole point of the parable: Frodo is a normal person trying to do the right thing in the face of enormous evil.
So if he doesn’t get snapped up by a ringwraith and killed, he just ends up as another Gollum.
And during Sam’s brief stint as Ringbearer, he has a vision of himself mastering its power… which he would use to make the world’s grandest garden. Because, at his core, a gardener is who and what Sam was.
And then, of course, because a humble gardener is who and what he was at his core, he then quickly realizes that forcing a grand garden upon the world through tremendous power loses the whole point of gardening, and that he’s better off not mastering the Ring, and just continuing to use his own two dirty hands.
Didn’t Sam having the ring in his possession at the time help give him a sort of glory when he was climbing up that tower where the orcs were holding Frodo, that made him seem bigger and more powerful, and scared the orcs (the few that were left after fighting each other to death)? Or was that just in the movie?
JRRT himself answered this one, in a letter to a fan. It’s quite a lengthy discussion, but for our purposes it is summed up like this:
“In any case a confrontation of Frodo and Sauron would soon have taken place, if the ring was intact. Its result was inevitable; Frodo would have been utterly overthrown, crushed to dust or preserved to torment as a gibbering slave. Sauron would not have feared the ring.”
Other extant writings of JRRT do discuss what would happen if very powerful people wielded the ring vs. Sauron. The summary was that only Saruman or Gandalf would stand a chance, others would most likely fall (if my memory serves me, at least).
And, yes, it did in one scene make him appear much more formidable and intimidating… to a few orcs. Think of it as a power multiplier: Compared to a couple of grunts, Sam-with-the-Ring was in fact a force to be feared. But to someone like Aragorn, it’d be "Nice try, but you’re still just Sam-the-gardener.
On the other hand, if Aragorn had the Ring, he’d be able to use it to rally huge armies to his banner, because his own personal power was much greater than Sam’s. And this was what Sauron assumed had happened, in his march to the Black Gate. Which was what made that march such an effective distraction: Aragorn with the Ring would be a sufficient threat that Sauron felt the need to crush him fast and hard (thus drawing attention away from the hobbits, who were even then almost to the heart of Mordor).
But as long as you have it, Sauron lives, and eventually he’ll dominate you. “There is only one Lord of the Ring, and he (He?) does not share power.” So it’s a perfect guarantee-you’ll never want to destroy it and therefore never rule the world. Ingenious.