Even if one accepts the argument that voting is not productive, that doesn't inherently justify not participating. There's plenty of things people do daily that are not productive or useful uses of their time.

Please demonstrate the harm caused by voting in the presidential elections.

Even if it's not productive, it takes at absolute worst case living in a hellscape without properly staffed polling places, one day out of your time every four years. I was able to do it and get back to my shit in 30 minutes this time, from the time I left home to the time I got back.

So even if it's useless, for me it was the same as sitting on my ass and watching a TV show. Explain why that is such a horrendous waste of my time that I should have instead not done it at all.