How do Individuals and Groups of People Influence the Political Process?

I would have and have said that individuals and groups of people have a great deal of influence in the political process.  After reading chapter 5, "Political Participation: Parties, Elections, and Movements", in the book, The Politics of Power, the authors write about how the Parties came about and how the elections work.  Also, they write about the amount of money that goes into the elections and how really, it is the people who contribute money to campaigns and candidates that really have the say.  The authors write, "[C]andidates are more responsive to wealthy donors and current voters than they are to non-voters.  They receive a better return on their scarce resources by investing in voters who tend to have strong partisan feelings and are likely to vote than those who are not.  I do understand why this would happen.  It would be a "waste" of "their" time to spend time and focus on low income and non voters. They do not have anything to contribute, as far as the politicians are concerned.  So unfortunate that, that is the way the world works.  I think that it is also interesting and sad that greed can get you so much in America.
After reading this chapter it was clear that we have a say if we have money and can buy our way in.