This seems to actually underestimate the value of voting, in that it assumes that a vote is only significant if it flips the winner of the election. But as Eliezer wrote:

But a vote for a losing candidate is not "thrown away"; it sends a message to mainstream candidates that you vote, but they have to work harder to appeal to your interest group to get your vote. Readers in non-swing states especially should consider what message they're sending with their vote before voting for any candidate, in any election, that they don't actually like.

Also, rationalists are supposed to win. If we end up doing a fancy expected utility calculation and then neglect voting, all the while supposedly irrational voters ignore all of that and vote for their favored candidates and get them elected while ours lose... then that's, well, losing.