You are likely not using the Adwords Keyword Planner tool correctly. When you type a keyword into it, it defaults to "broad match". This means that it will show you how many people search for your term and all related concepts. From a practical perspective, that makes it look like there will be much more traffic on your term than actually exists.
Instead of using broad match, you need to set the tool to "exact match" mode. That way it only shows people who searched for exactly what you are ranking for.
Actually, it looks like Google took the exact match functionality out of this tool. It doesn't look like the Adword Keyword Planner is useful for estimating search volume any more. The closest thing they have now is a setting for "Only show ideas closely related to my search terms":