"Well, that may be true for you, but it's not for everyone."
This kind of unconsidered relativism has made it's way into American parlance.
How might we respond? Here's a suggestion:
"What is true is true. For example, it is always true that east is east and west is west. Even if I am going east, and think I am going west - that doesn't change the truth. So, I need to change direction -- not expect direction to change for me."