There was a vote that happened in my youth where two parties ended up with (Edit: NEARLY) identical amounts of votes in the house. In my voting district there was an independent running who was fairly popular with the city and we voted him in. The end result was that during legislation there was some vote where the yes/no vote was split perfectly even between the two major parties and our little independent became the deciding factor Edit: My memory was faulty. He forced it into a tie with his vote and the speaker of the house had to be the tie breaker. But the point still stands that his one vote had a pretty large implication.
This is a very niche and unlikely scenario (it did happen though, look up Chuck Cadman) but it was a very clear indication to me that yes, voting does matter. And every one single vote DOES count and make a difference.