Sauron and Saruman?

[the phantom]

A small mind would become enslaved to the Ring and therefore be overpowered by it. But it never says it would do the same to a great mind

I believe that it's just a matter of time. I don't think anyone can use the ring and not eventual be overcome by it. It might take a long time, several thousand years maybe (just think of how it'd be to fight a battle of wills for that long), but the wielder would be poisoned more and more with the passage of time.

To even claim and use it means the person has already been influenced by the ring, and obviously the influence grows with time since they eventually become the new Dark Lord. And if the influence of the ring grows with time, I think it would eventually move beyond influencing the wielder to greatly influencing the wielder and then to commanding the wielder.

But if that's not how you view the ring's power, then I guess we can't agree on this. I subscribe to the theory (which many don't like) that Sauron's ring plot was perfect. No one could ever destroy him while the ring existed, no one could willingly destroy the ring, and anyone who claimed the ring would eventually bend to the ring's (Sauron's) will. I believe that Eru's divine intervention was the only way for people not named Sauron to win.