The most obvious answer to this question is, of course, to protect your idea. Based on the nature of your idea, there may be people ready and willing to patent your idea if you have not already done so.
The application for a patent gives the owner of the idea the best opportunity to profit from the idea while, simultaneously, preventing others from copying it for their own benefit. However, although a patent prevents others from copying your idea, you do not have to have patent an idea to be able to exploit it.
It has often been said that for every idea that you have, a few hundred people around the world have already thought of the idea. Although this may sound disappointing, consider this: most of those individuals have, more than likely, not opted to patent the idea themselves.
One of the main reasons that I suggest applying for a patent for your idea is that it gives you ample amount of time to get your invention noticed by potential investors or businesses who may be interested in partnering with you on the idea. An inventor who has a patent, which is a form of commercial property, is much more appealing to investors as it allows the inventor the ability to more readily negotiate.