Just remember that when you vote for the President, you are not just voting for the candidate, but also for the party that candidate represents.
Because the President will fill his cabinet primarily with people who are from his party. He will nominate judges to the courts that are acceptable to his party. He will usually sign legislation that is embraced by his party.
One party believes that Planned Parenthood should be outlawed and uses fraudulent videos as an example. One party is against a minimum wage hike and would like to eliminate it altogether. One party is for making abortion illegal in most circumstances. One party wants to weaken unions. One party wants to repeal Obamacare and does not have a replacement for it.
The party that wins will have more power to enact or oppose these positions. If you like them, then not voting makes it harder for these changes to be enacted. If you don't like them, then not voting makes it easier for them to be enacted.
Unless the Senate changes its mind in the next few months, the next President will choose at least one new Supreme Court justice. Trump has already said he will rely on the Heritage Foundation to advise him on his choice. If you prefer that to some other advisors, then vote for it. If you don't, vote the other way.
It may seem that there is no real difference between the two candidates. And maybe there really isn't. But don't just look at the candidates. Don't just look at whether they are "pro-establishment" or "anti-establishment." Also look at the parties they stand for, and everything those parties stand for. And only then, if you really believe there is no real difference between the parties, if you really feel that it doesn't matter one bit which candidate and party gets elected, then you can say it doesn't matter and not vote.
But if you have even the slightest preference between the parties, then vote for the one you prefer. Because there are real differences that I see between the goals of the two major parties. And I believe it may make a real difference which one gets elected come November.