The Lord of the Rings, at its heart, is a tale about people, and the different paths they take on their journey towards corruption, redemption, or actualization. In Middle Earth, there is a constant state of unimaginable wars, sources of darkness vying for power, and entire races of orcs and goblins whose sole purpose is to take control and obliterate anyone who opposes the dark-lords rule. In such a world, it is amazing that there are still characters like Aragorn, who is loyal and brave and shows compassion above all else; or Frodo and Sam, whose love for one another and their peaceful home in The Shire is strong enough to move mountains. But between the heroes and the villains, there’s a middle ground, where characters like Isildur and Denethor and Saruman reside. These characters, driven by greed and power, are all aiming for one thing: to be the next dark lord.
In order to do so, they would need to have possession of the One Ring, the most evil object in Middle Earth. The ring twists and temps people’s base desires, and manipulates peoples will until they are unrecognizable. Isildur came close, when he had the ring in his possession, to total corruption, until the ring betrayed him in favor of a new master. And Saruman almost certainly could have done serious damage if the One Ring had actually landed in his hands, perhaps enough damage to be able to challenge even Sauron for his seat of power. But if the ring is key in instigating where the power lies in the world, why did Gollum never rise up and seize this power, when he had the ring for nearly 500 years?
The simple answer is that power begets power. Those who start out in a position of great power are far more likely to be able to seize even more of it, whether for good or for bad. This is why both Gandalf and Galadriel are horrified when they are presented with the possibility of obtaining the One Ring. For example, when Frodo offers it to Gandalf, the grey wizard responds:
“Don’t tempt me, Frodo! I would take the ring with a desire to do good, but through me, it would wield a power too terrible and great to imagine.”
As Gandalf is a maiar, and already has amazing abilities of magic and fire, the ring would be able to harness these gifts and corrupt them, creating a truly terrifying dark lord.
The same goes for Galadriel, who experiences many traumas in the First and Second Age of the world. Those traumas make her remarkable strong and resilient, and give her the ability to wield all sorts of powers, including seeing visions of the future. She also is tested by the presence of the ring, and turns into the fearsome green glowing version of her power as she yells:
“In the place of a dark lord you would have a queen! Not dark but terrible and beautiful as the dawn! Treacherous as the seas! Stronger than the foundations of the earth. All will love me and despair!”
This is a perfect demonstration of the devastating effects the ring can have, when used by an already powerful being. Gollum, on the other hand, has far more humble origins. He is believed to be something akin to a hobbit, perhaps stemming from one of the three types of ancestors: Harfoot, Fallohide, and Stoor. As such, his innate love of a simple life, surrounded by things that grow, good food, and good company, must still be in him somewhere, even when is corrupted by the ring. All memory of that long ago existence has begun to fade.
Hobbits are particularly resistant to the ring, namely because they want nothing more from life than peace, and having descended from the same ancestors, this is the same for Gollum himself. Gollum didn’t start out as a powerful being when the One Ring first came to him, unlike others that it had corrupted in the past. He had no desires to seize such power, even after the many long years of having the dark object twisting his mind. He was therefore never going to become a dark lord, or try to challenge Sauron for this claim. Instead, all he wanted was to live a quiet and unnoticed life in his dark cave below the mountains, nonchalant to the affairs of the world outside.
The ring, of course, knew this. It was only ever biding its time with Gollum until a more important and already powerful master presented itself, one that the ring could actually use to achieve its nefarious purposes. It never actually intended to fall into Bilbo’s hands, nor into Frodo’s, because they were the same quaint beings who had no desire for dominion, much like Gollum. This is why why the ring tried so hard to corrupt others around the hobbits, like Faramir, who was able to resist it, and Boromir, who was not so fortunate.