Campaign Finance Law Overturned

The Supreme Court ruled that corporations can spend as much as they want on behalf of candidates, overturning a previous ban on corporations directly influencing elections, as detailed in articles like this one, from the New York Times.

I am not a big-business type and care more about the rights of everyday people, about the environment, about trying to right injustices in the world, about things that can't even be measured in dollars, like music and love, than I do about businesses' rights to make inconceivable amounts of money.What are people like me going to do if big businesses start to control who is elected to represent us and then bribe and blackmail the politicians into doing their bidding? 

My first thought was that the only way for people like me to fight big businesses would be for us to start a big business of our own and make a lot of money to support our candidates.  But I suspect that, in order to make enough money to rival big businesses, we would have to start exploiting people and the environment.  And if our goal became to make a lot of money, we might start to change our ideas of what we want government to do for businesses at the expense of other priorities.  We would, in short, defeat ourselves trying to defeat our adversaries.  We would become the people we set out to rival.

There's a particular big business I'm thinking of, generally of liberal bent, whose CEO did, in fact, speak out against a social program under consideration now.  It's probably an example of what could happen if a well-meaning group of people set out to make a lot of money.

What to do?  Maybe try to live in spite of the government instead of trying to change the government. Power leads to corruption and corruption seems to be necessary to rise to power. 

Yet people don't function very well without power structures.  Groups need leaders.  Even in my apartment, I have to take charge for anything to get done.  People don't just take on responsibilities of their own accord.  The same is true of society.

How can an organized society have a government to deal with common problems without it becoming corrupt?  Is this one of those insoluble problems?  I am trying not to throw up my hands, but I am throwing up my hands.