The "issue" with that is that, typically, most elected officials work their way up the ladder. Generally speaking, first, they're mayor of a city, then governor, then they typically run for a federal office, be it president or congressman/ congresswoman. If they run for Congress, there's a chance they may run for president later down the line.
There are other options to pick from in a climb to the top, so this is just a general idea. Basically, they have to make a name for themselves on the national political stage before they have a chance at winning the presidency. So that's what they try to do when working their way up the ladder.