why Frodo?

[Eldar14]

I don't think that Frodo's kindness towards Gollum was because he was such a good Hobbit. Yes, Frodo was good inside, but I think his kindness had other motives. I think Frodo was nice to Gollum because he needed proof that the ring couldn't corrupt him all the way; he needed to know that he still had a chance of always having that bit of good deep down inside of him, regardless of what power the ring had over him.

Maybe that's one reason why Frodo did it. If Sam had been the one to bear the ring, his motivations would have been to save Middle Earth. To save the Shire and Rosie and all of that. But maybe Frodo had the slightly personal quest; he had seen the effect of the ring on Bilbo, and the effect it was starting to have on him, and he felt that he had to destroy it to save himself. Regardless of how good of a person you are, the motivation to save one's own skin is a very strong motivation, even stronger than the one to save the world.