[akhtene]

I think that's because Smeagol (Gollum) wanted it, and killed for it, and finally left his people... Whereas Bilbo just found it by chance and didn't think much of it. If it wasn't for Gollum again, who was tortured in Mordor and let out Bilbo's name, I think the Ring could stay in the Shire for quite a lot more time. So it foung a wrong keeper (from its point of view)