Using the 14th Amendment to give corporations free speech rights combined with the belief that campaign contributions are a form of speech is a big part of the problem. The intention of the 14th Amendment had nothing to do with corporations but someone wanted that hack and the consequences have been immense.

If we went back to campaigns being funded by individuals, the pandering to mega-corporations would be significantly reduced. Since wealth disparity exists, it still wouldn't eliminate the influence of wealthy donors but without corporations being able to effectively purchase elected officials, it's likely that wealth concentration would also be reduced.