Much of the funding behind the tea party movement, right wing media, “think tanks”, the armies of pundits on every cable news channel, “grassroots” conservative issue-advocacy organizations (including Citizens United, for instance), anti-Democrat conspiracy books, and so on comes from completely unaccountable and often anonymous billionaires.

Campaign finance laws actually have significant influence on how much money can be spent, how transparent the funding must be, what money can be used for, etc. Media regulations also have a large impact.

A particular fringe world-view doesn’t just pop into significant numbers of voters’ minds out of nothing. It is deliberately tended and promoted by folks with large amounts of money with specific policy goals.

See e.g. this interview with Jane Mayer about Bob Mercer from yesterday, http://www.npr.org/2017/03/22/521083950/inside-the-wealthy-f...