Assume the value of difference between two candidates is half a trillion dollar (reasonable with crises, iraq etc.).
With twenty or less million votes being critical, the probability of a. Sngle vote changing who is president is 1/20,000,000.
The expected value of a single vote is the soceity value ($500,000,000,000) times teh probability of the vote being pivotal. * 1/20,000,000
==== $25,000 value of a single vote.
This is the value for soceity.
Thus, if voters care about their soceity as a whole, they are very reasonable in spending one. Hour to vote and giving. The public $25,000 in value.