Gollum came to appreciate the Ring's power over him. He started out with
envy and murder in his heart, and started his ownership with it with the murder
of Deagol. As has been pointed out, the Ring took his weaknesses and
played on them. With the Ring he became a serial murderer, as even
killing Orcs is murder in the manner he killed them.
Bilbo found the Ring, and didn't purposely take it just to possess it. He
started his ownership with it with mercy instead of evil actions, and used its
power only to assist others. He was not a great enough person to try to
do more good than that necessary for himself and his companions, so it was
harder for the Ring to ensnare him through personal pride or ambition.
And once home, the only time he used it was to escape the attentions of the
Sackville-Bagginses. He never realized what the Ring was, where it came
from, or what its discovery meant to the world of Middle Earth. His very
ignorance of what the Ring was, its power and its nature, also served to
protect him.
Frodo, on the other hand, learned the nature of the Ring and had far more
appreciation for the evil it represented, particularly as he saw two of the
greats of his day actively deny it (Gandalf and Galadriel) and two others
(Elrond and Aragorn) from the first seeing it needed to be destroyed. He
also came to this knowledge after the Ring had begun to awaken, after Sauron
had begun to recover his powers and to call for it to return to him. He
carried it the furthest with the most knowledge of what it could do to him and
to others. He had seen Gandalf's naked fear of what the Ring would do
through him if he kept it, and saw Galadriel's appreciation for what she would
become. And he heard Boromir's plans for what he would do with the might
of the Ring at his command, and had an appreciation from what Gandalf and
Galadriel told him of how this was a trick of the Ring's--to ensnare a new
bearer.
For Frodo, at the last, there in the seat of its power, at the last it
overwhelmed even him. He'd been able to withstand it for the longest
time, partly because he was a hobbit, and hobbits aren't particularly ambitious
folk to start off with. He was a gentle soul, and gentleness wasn't
something the Ring could catch hold of easily, either. He was
compassionate, and that was another trait the Ring would have a hard time
using, although Gandalf indicated that would be the strategy the Ring was most
likely to use in ensnaring himself. He never killed along the way, which
left him without that kind of guilt to use in corrupting his soul.
I was glad, however, in seeing the films, to recognize that even at the end PJ
and/or Elijah let that one short glimpse of horror at claiming the Ring be
expressed by Frodo before he returned to the sneering smile worn by Isildur
when HE claimed the Ring. There was no hint of that in the books, of
course, but to see it there in the film was in some way reassuring.
For, in the end, it wasn't truly the individual who claimed the Ring who was
doing the claiming--it was the Ring claiming another victim
instead.
"Then do not be too eager to deal out death in judgement. For even the very wise cannot see all ends."
"Don't go where I can't follow!"