I think everyone who goes bare belly in public don't have navel fetishism in mind when they do. As mentioned before, they are only doing it for the style, overcoming the heat, or just being proud or confident about their bodies.
Now, girls who draw attention to their bellybutton by getting a tattoo around the bellybutton, or having rhinestones around their bellybuttons, those are girls more likely to be one of us and wanting their buttons to be the center of attention.