A lot of that money goes towards legitimate expenses like money for offices, phone lines, electric bills, travel costs, and most importantly, pizza and caffeine for campaign volunteers. That money also goes to pay salaries for the paid staffers, who have left behind other jobs to devote themselves completely to the campaign. They don't always get a lot of money, and if the campaign finds itself short on money, they might get a few IOUs instead of actual paychecks, but that's fair because they are putting in long hours and doing a job that probably can't be trusted to the college interns. Finally, a distressingly large amount of campaign cash goes to "pollsters" and "consultants."
Firms like Mark Penn's Penn, Schoen, & Berland Associates LLC are among the recipients of large amounts of campaign dollars. They ran up millions of dollars in bills for Hillary Clinton's failed presidential campaign, going after Obama even when the end for Hillary was in sight. But still, to say that Mark Penn is the problem is scapegoating, pure and simple. The problem isn't that people think up the stuff that wins voters, it's that voters are so ill informed on the issues that big spending can tilt the scales and win an election.
If the American people were well enough informed on the issues facing the country, then all the billions of dollars in corporate America wouldn't mean much. But because of our ignorance and our apathy, a few million here and a few million there make a big difference come election day. So, due to our inability fulfill our responsibilities as citizens of a democratic republic, the Supreme Court ruling, that will allow unlimited corporate money to pay for ads for or against any candidate, will further the problems of money in politics.