system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] Why does the Ring abandon Isildur after only a few years when it stays with Gollum for centuries and Bilbo for decades ;

Was Isildur great enough that the Ring could actually be effectively used against Sauron and thus would be too dangerous‏‏‎‏‏‎‏‏‎‏‏‎­to keep in Isildur's custody?
gpt
The Ring abandoned Isildur at a time where there was a relatively high chance of it falling into the hands of the enemy; during the middle of a battle against Orcs. The likeliest outcome was that the Orcs would claim it.

Same thing happened with Gollum. It abandoned Gollum in the depths of a goblin infested cave. Again, the likely outcome was it being claimed by the enemy. As for why it abandoned Gollum when it did and not sooner, until that time it was content to wait. There was no rush for it to get back to Sauron, who was still recovering his strength from his defeat on the plains of Dagorlad. But once Sauron was ready and was actively preparing for war, the Ring took the first opportunity to leave Gollum.

And no, no one could truly use the Ring against Sauron. In doing so, they would end up falling in exactly the same ways he had, and he would just wait to take it from them. Unless the Ring was destroyed, Sauron couldn't be beaten, He could be scattered, weakened temporarily. But only the destruction of the Ring would defeat him permanently. Thus, all he would have to do is wait for the bearer to become corrupt, and then take it back from them.