The purpose of voting was to replace the devine right of kings as a way to get people to acquiesce to power, when people called bullshit on kings. Oligarchs told the people they would be in charge by voting. People bought it and continued to allow themselves to be ruled.
Voting is pointless, from the voter's perspective. Your vote has a snowballs chance in hell of having a positive impact, on your life, in a predictable way. You also know this. Not only do you have to be the tiebreaker, but you have to have something worth breaking a tie in and have foreknowledge that doing so will help you. Being a tiebreaker is very rare and knowing how a politician or policy will play out is impossible.
People are heavily influenced by the crowd and can be made to believe (at least on the surface) and repeat false things, just because many other people believe them. Our brains are made this way because group cohesion has historically been very important to human survival. If the entire tribe believes something, you believe it too, even if it seems untrue. If you go against your tribe, you might get forced out and die.
This is why bullshit breaking movements start out very very small and then everyone believes it. Take marijuana legalization. The bullshit making it illegal was foisted on us by nearly a century of bullshit pedaling propaganda. Just moments ago, it seemed most everyone was against legalizing it except for a few loud minorities. Over time though their numbers grew and then BOOM everyone is for it now. A rare minority is convinced by the truth. The rest are convinced by the fact that that is what everyone else near them and to a lesser degree, in society, believes.
Everyone, somewhere deep down knows that voting is bullshit just like they knew putting people in cages for having post was bullshit. They vote because masses of people do so and there is great, "get out the vote" propaganda telling them their knowledge is wrong. People look at how many people are voting and not voting, especially people they know but also the statistics that get reported. It impacts whether or not they can be brainwashed.
The get out the vote propaganda is so loud and in for your face because the idea that voting is a good way to improve your life is so preposterous that people keep leaving the belief. So "get out the vote" is a drumbeat people keep repeating over and over again, half to convince themselves because they are afraid of what it means if it's untrue and half to convince you who are leaving the practice because of the same fear.
Not voting records you as one of the people who are calling bullshit. It gives comfort to someone else who feels like calling bullshit but is afraid to do so because everyone they know votes. The fewer people who vote, the faster people will call bullshit on it. When it snowballs and the masses of people realize ( or rather feel safe in knowing) that they cannot positively affect their own outcome by voting, they will try something else. When the people call bullshit on voting, like they called bullshit on the devine right of kings, the system is over. Then we can try a better way to live.