My theory is (and I'm sorry if it's wrong!):
That basically, men are weaker than the other races and Sauron and/or the Ring are using this weakness in order to corrupt them (e.g. Boromir)
They start out (Boromir) with wanting to use the Ring with the will of performing good deeds in order to help Middle-earth but because the Ring knows of the desire to use it and knows of Men's weakness, they use this combination of things in order to corrupt them and to tempt them to try to take the Ring.
Just an idea I had! 😮