To clarify, since I imagine this is somewhat difficult to discern from a 150 character title limit:
Why is it that a resident of Rhode Island may donate to a candidate in Florida in order to bolster that candidate's re-election? It seems like a flagrant conflict of interests, as now the candidate can be beholden to the interests of a person outside of the district that they (ostensibly) represent. While obviously the Rhode Islander may not vote for or against the candidate, there's a strong correlation between money spent on a campaign and the probability that that candidate will win an election.
Phrased another way: What are the arguments for why a candidate should be able to accept donations from individuals and businesses outside of the district or State that they represent?