Politicians can't just appoint themselves to Congress or state legislatures. You may think they're idiots but citizens are voting for them. Is it possible that some of those "idiots" aren't as stupid as you think but rather just have different priorities and values?
People are ecoring for them and others (include you, whoever reads this) don't compete with them and challenge them.
Politicians are optimizing for one objective: to be re-elected.
This is very different one from the objective I want them to focus on: improving the lives of their constituency.