There aren't all that many things I believe today that I credit Ayn Rand with, but one thing her work helped me clarify and understand was an observation I'd made early on in middle school or high school about self-deception.
People lie to themselves all the time. People lie to the rest of the world all the time. Their ideas and values are often a mishmash of contradictory garbage that they've never had the courage to sift through and sort out, and the only way to continue operating in life without having a daily meltdown is simply to ignore the contradictions and move on.
The problem with all this is that reality asserts itself no matter what you wish to be true.
You can pretend you're a "wolfkin" or some kind of shaman that controls the weather, but in reality... well... you're not. And as much as you might claim otherwise, deep down, you know the truth. We all know the truth. Because reality wins.