Many people can "see" opportunities in all sorts of things. It's just that most don't do something with them.
It's like spotting an attractive woman/man by her/him self at the nightclub, pub or wherever. Seeing what's in front of you is the easy bit but it's not going anywhere if you simply ignore her/him. You have to do something, taking a risk in the process, in order to achieve any benefit from the opportunity presented.
Good analogy - it comes down to self-belief, confidence, guts, more or less anticipating that taking the risk will pay off, or being prepared to wear a bit of pain and get out fast if it doesn't. Prior research of great benefit. Those that suffer from fear of rejection/failure, uncertainty/timidity, lack of confidence etc will let the opportunity pass them by...
Then there are those that already are content with what they have and simply want to preserve it - ignoring a new "opportunity" may often be the best course to take in that case