There’s actually a lot of debate on the actual value of money in a campaign. While it’s clear the guy with the most money wins what’s not clear is if one causes the other and if so which one. Nobody has ever managed to come up with an equation that relates dollars to votes, which seriously damages the idea that money makes a winner. On the other hand the guy with the most votes generally has the most donors (which is how he gets the most dollars). So the stat seem to indicate that donor money is really nothing more than a very accurate poll, the candidate getting more people to give him money is going to get more people giving him their vote.
The problem with the "national primary" in this context, though, is that the donor decisions and money distribution takes place in advance of any vote. There is no opportunity for the underdog to come from behind -- which is the circumstance that most non-establishmentarians desire.