"Voting doesn't matter" is the stupidest myth I continue to encounter. Voting matters A LOT, which is why certain political parties try to restrict it as heavily as they can.
Every election cycle, monied interests spend billions and billions of dollars on ads alone to influence as many voters as possible for a reason. They know the power of a vote, and spend their vast resources accordingly. Pretending voting doesn't matter makes you a useful idiot at best.