Julien's comments above apply to most patent but not all. The initial patent in an area even for a startup is important to have. The first microwave, airplane, radio, cell phone, etc. are possible examples.
Vanay also has an important point. Your patent idea should be confidential, but to be afraid of sharing it then you will never obtain the help needed to move it forward. A non-disclosure agreement is important to get if possible but it is a worthless piece of paper if the agreement is with a dishonest person and is not needed with a very honest person.
Just think about the images of people put on the internet. Yes you can bring charges against the person that steals or takes the image without permission, but you can not do a thing to the people that view it and do things to increase viewing. ( assume I have properly understood the TV attorneys discussing this issue)