I disagree, voting does make a difference.

Each vote cast gives credibility to the political system and to the politicians.

Voting the best way to choose which politician you believe will use the violence and force of government to coerce others to behave the way you know is best.

Also, voting gives you the right to wear an "I Voted" sticker, and signal to others that you are a dutiful citizen.

Voting is not like a placebo, as placebos tend to do no harm.