It is about the money
How it's raised. How it is spent. Where it comes from.
It matters.
Only 17% of a certain Democratic candidate's donations come from $200 or less according to OpenSecrets. Over 63% of contributors have already given the maximum legal donation for the entire campaign cycle, primary and general, to that candidate's campaign.
What about Bernie Sanders? OpenSecrets states that 74% of his donations come from $200 or less. Only 1% of Bernie Sanders campaign contributors are at the legal limit for the campaign cycle.
Donaton information for all candidates (amazing article):
http://www.nytimes.com/interactive/2016/us/elections/election-2016-campaign-money-race.html?_r=0
Great quote from another article:
"If Hillary Clinton cannot knock out Bernie Sanders early on, she will find much of her donor base is maxed out while he can keep the money flowing with simple email appeals that cost him little more than the processing fee on the credit card."
http://www.forbes.com/sites/jeffreydorfman/2015/10/26/bernie-sanders-ben-carson-use-internet-to-show-campaign-donation-limits-are-irrelevant/