Well, since ideas can be patented, trademarked, become intellectual property and whatever else, it's understandable that we feel scared about ideas being stolen

Well, since ideas can be patented, trademarked, become intellectual property and whatever else, it's understandable that we feel scared about ideas being stolen. But I think the roots of the problem are basically in our enthusiasm and our (lack of) self-confidence. On one side, we consider our ideas awesome and that anyone who hears them will also think they are the coolest thing since sliced bread. On the other hand, we believe that, if they like it enough (which they obviously do because of the previous point), they will steal/copy it and possibly execute it better than us (because they have more experience, more people, more contacts, more money... infinite reasons). This article speaks the truth, 99% of the time people won't care or understand, and you will have to chase them to make them believe in your ideas (I'm experienced with the "that's interesting" people :P). But when enthusiasm is strong enough, it's very hard to accept that someone won't like your idea. And if self-confidence levels are low, here comes the problem and the secretive attitude.