What's the main reason voters choose political candidates

Political candidates know how government system works, they study this stuff for a living, for a example. Let's say you are hiring someone to be your lawyer and you have 2 options. One knows a lot of about law, they have "Master of Laws" Master's degree and or other option is a man who is famous that has a lot of public influence. You would want the guy who knows a lot about law that best fits that role, same way in politics, you want someone who has experience and knows how the system works.