How do you explain reentrancy in interviews without sounding like you memorized it?

I keep practicing smart contract interview questions, and reentrancy comes up every time.
I can say the rule: “Do Checks-Effects-Interactions.”
But when they ask why the order matters, I struggle to explain the actual risk.

How does the attacker still use their old balance?
Why does the whole contract state not update in time?
And what exactly makes Pull payments safer than Push payments when money is on the line?

I don’t want to recite textbook lines and sound like a junior who’s just memorizing stuff.
I want to understand how seniors think about reentrancy so I can explain it confidently in interviews.

If anyone has a moment where this finally clicked for them (test, diagram, code review), please share 🙏
Your experience might help a lot of us preparing for Solidity roles.