How often does a single vote decide an election? Never? Therefore your optimal move is not to waste your time voting - you gain nothing. If everyone thought that way it would be bad perhaps? But they don't so it doesn't matter to you.
It might be argued discussing politics contributes to some emergent consensus forming that benefits society, but that consensus will form whether you participate or not and in exactly the same way unless you win the social lottery and have a disproportionate influence. So you are better off not wasting your time on political discussion, just keep track of the political trends the same way you would keep track of the trajectory of a storm heading towards you.
Tragedy of the commons applies to potential just as much as it does to existing resources. The Nash equilibrium is to consume all the resources you can right down to exhaustion because you alone cannot preserve them and others will consume them whether you do or not.
It is also a Nash equilibrium to conserve your time and not spend it on activities that would benefit the collective but not yourself - in the presence of a collective your contribution (and therefore influence and gain) approaches zero.