The friend who radicalized me is now begging me to vote for Harris

the reason you can't provide a counter argument is that his position is completely incoherent. Not saying that just cause I disagree either. You posted 1 sentence that has 4 or 5 different thoughts that are irrelevant or contradictory to each other. Maybe the reason he likes kamala is they are on the same wave length in terms of cognitive context?

But seriously I don't know if logic is the name of the game here. If you are going to try to reciprocate the gift of communism and pull him out of the pit, I wonder if checking for emotional salience might help. I would ask who or what has changed his mind? There could be a relationship: with a person, group, identity, even a parasocial relationship or other indirect influence, that has contributed to this. Or has his relationship to his context changed? Has he discovered a new/latent class allegiance? One of the various trains of thought mentioned is "this time its not like doing this abstract process". What the heck has changed to make it concrete/direct now? Nothing has changed in the system to make it more tangible. If something's different, it's him.

I'm also curious about the variation between the post title and the body. The latter is his weak ass attempt to justify his own behavior which is one thing. But why does he want you to do the same so badly? Surely he knows "might as well" isn't a compelling argument for anything. I won't leave my house for "might as well". Might be downplaying his own commitment to avoid cringe. Or maybe he really cares what you think and wants you to endorse his behavior. Or he has adopted a new theory of change that involves each person getting one other person to vote. In any case, if you can draw that out, it would be clarifying for you both.

I personally don't see the fascism inherent in this small amount of information that others are pointing to. I have heard some almost-compelling arguments made on the issue of abortion alone. I can imagine if I was a different person, with different experiences, and less stubborn, I could be swayed if it came from the right source. We are all influenced by those around us. Some people are really easily influenced.

To inquire in the opposite direction, I might ask him what would convince him to change his mind. Perhaps leading in the direction of a viable political organization to join and act with. Evidence of class power. Instead of focusing on his current trajectory, imagine a different one. A few minutes of world building to get out of your heads.. Imagine a left that wasn't in utter disarray, would you still be making the same argument? If not, why? Because there would be hope! What would it look like? Now is that what the democratic party looks like? Is that what it feels like?

At the end of the day, there are some lessons that can only really be understood and internalized through struggle. You can learn in 30 minutes of experience things you can't learn in 30 years of reading and discussion. Has he done anything communist or was it more of a talking thing? If not, he should.