Edit: Oops, cross post.
The campaign buys the ad, the commercial, etc. et al from money they’ve raised from donors.
See for example Bernie Sanders. He raised $20 million in January, average contribution of $27.00
We chip in, the campaign does the campaigning. That’s representative democracy.
It is fundamentally a question of fairness. On that I am sure we will not agree. :)
Here’s a fascinating article on Vox from some psychological researchers (with an unfortunately clickbait title: Donald Trump supporters think about morality differently than other voters. Here’s how.) http://www.vox.com/2016/2/5/10918164/donald-trump-morality
Long, but really worth reading.
The premise for their Moral Foundations Theory:
[ul]
[li]Care/harm: We feel compassion for those who are vulnerable or suffering.[/li][li]Fairness/cheating: We constantly monitor whether people are getting what they deserve, whether things are balanced. We shun or punish cheaters.[/li][li]Liberty/oppression: We resent restrictions on our choices and actions; we band together to resist bullies.[/li][li]Loyalty/betrayal: We keep track of who is “us” and who is not; we enjoy tribal rituals, and we hate traitors.[/li][li]Authority/subversion: We value order and hierarchy; we dislike those who undermine legitimate authority and sow chaos.[/li][li]Sanctity/degradation: We have a sense that some things are elevated and pure and must be kept protected from the degradation and profanity of everyday life. (This foundation is best seen among religious conservatives, but you can find it on the left as well, particularly on issues related to environmentalism.)[/li][/ul]
A graph:

But it revealed something else: Despite often being portrayed as opposites (Rubio is “establishment”; Cruz isn’t), and Cruz being seen as more aligned with Donald Trump, Rubio and Cruz actually draw from voters with a similar moral profile. Each would probably be doing better in the polls if the other weren’t in the race
The premise of their Moral
Cruz and Rubio draw the extreme proportionalists — the Republicans who think it’s important to “let unsuccessful people fail and suffer the consequences,” as one of our questions put it. Bush and Huckabee attract those who are not so focused on enforcing proportional fairness. Trump and Paul fall in between on this dimension.
One surprise in our data was that Trump supporters were not extreme on any of the foundations. This means that Trump supporters are more centrist than is commonly realized; consequently, Trump’s prospects in the general election may be better than many pundits have thought. Cruz meanwhile, with a further-right moral profile, may have more difficulty attracting centrist Democrats and independents than would Trump.
One last interesting finding: Jeb Bush supporters are closest to the average American voter, despite the fact that his campaign has thus far has failed to gain any traction among Republican primary voters.
And finally their conclusion:
Politics is in many ways like religion: Voters reward candidates who are effective preachers for a set of moral concerns. Candidates who understand this realize that electoral campaigns are not won just by articulating the most effective policy responses to the pressing issues of our time — they are not even won by appealing to self-interest.
Rather, an effective political preacher offers a clear moral vision of America. That vision includes a historical narrative about where we went wrong, and then tells us how we can set things right. It also includes strong moral arguments that connect with and validate the moral judgments of voters.