My state would’ve gone to Harris no matter who I voted for.

Ok, that's actually a reason I accept.

So, the argument you have is that voting doesn’t matter individually, only in aggregate.

Not entirely. In democracies that e.g. use coalitions to get the majority, like a lot of european democracies, this absolutely makes a difference. But the USA just naturally leans towards this 2-party system. Which btw. degrades the "democratic" aspect quite significantly (i.e. USA is quite low on the democratic index compared to e.g. Norway).