This NPR article on Weedgate is right on the money:
A quarter-million dollars in online ads is now supporting a third-party Senate challenger — Libertarian candidate and pizza delivery guy Sean Haugh. The ads are coming from an unlikely source: the American Future Fund, a secret-donor political group….
The $225,000 is nearly 30 times more than the $7,744 Haugh said he has spent for himself.
To put that in perspective, the two main party candidates and outside groups have already spent $85 million on the North Carolina Senate race in advertising that directly tells voters to support or oppose a candidate. Nonprofit political groups that are allowed to keep their donors secret, including the Koch brothers-founded Americans for Prosperity, have spent tens of millions of dollars more in so-called “issue” ads attacking Hagan.
“You have to wonder why people are willing to spend up to $100 million to elect somebody to a job that only pays $174,000 a year,” Haugh said.