Probably long after I should.
But if explaining does not work, I do have a few other tools in my toolkit before I give up. One is metaphor and analogy. Another is relating it to something in the other person’s own life. And another is asking questions, carefully, respectfully, trying to get at the “what” and not the “why” that is the obstacle. Many failures to communicate come down to (a) different definitions of terms and (b) unexamined assumptions.
But some people just aren’t going to get it. It’s okay. Walk away. You are not responsible for everyone’s perfect understanding.
And anyway there is always (always) the possibility that the one who does not get it is you.