When SmeagolSméagol found Thethe One Ring, it was not long after it had been lost by Sauron himself, with only Isildur holding it for a very brief time, deciding not to destroy it. It was still strong with dark powers, and there immediately was a quarrel between him and one of his relatives for the ring. It was easy for the Ring to corrupt him rapidly.
For Bilbo, the ringRing had been lying dormant for decades, and when he found it no one was around but himself. He kept it in his pocket most of the time and didn't come to realize its power right away.
For Frodo, the ringRing had been in posessionpossession of his Uncle, a very unassuming and peaceful creature, and one who was very resistant to the ring'sRing's power from the start. And it had been lying mostly dormant, since Bilbo hadn't much need for it in daily hobbit life.
And for Sam...well, he only used it once and very briefly, albietalbeit deep in the heart of Mordor. His love for Frodo was impressively strong, he'd only had it for a few hours at most, and the natural resistance to ring-corruption hobbits have likely helped.
In each of these cases though, it was still very hard to give up the ring. For Bilbo, it took every ounce of Gandalf's cleverness and convincing to get him to part with it. And for Sam, it took his own steel reserves to hand it back to Frodo.
SmeagolSméagol was just unlucky - he found the ring when it was most powefulpowerful, was tempted early on to commit a very violent act, and did so, thus sealing his corruption. It's also implied early on by Gandalf, when talking about Gollum, that the type of 'Hobbit' he is/was isn't quite as peaceful a creature as Bilbo/Frodo/Sam. Which may have meant less resistance to the ring's corruption.