It's not useless cynicism, it's a sober approach. Understanding that the influence of politicians is delimited by their knowledge, the as well as monied, and bureaucratic interests.

I vote in every election I can, national to local. But ultimately you have to understand that in most cases, unless you're willing to dedicate your life to political advocacy (an exhausting route filled with small corruptions, traps of necessity that threaten your principals, and unpleasant people) you're choosing to adjust the angle of the rudder within a certain margin, not the trajectory or shape of the ship.