my parents don’t understand how hard engineering is

I’m pursuing aerospace engineering next school year for college and I was talking to my parents about how hard some of the classes are and they told me they expect me to get all As or else they refuse to pay for my college. Based on many people’s experiences they share on Reddit, getting all A’s as any engineering major seems close to impossible. Is there any way I can convince my parents that it’s very hard? I’m going in with the mindset that I’m going to achieve the highest grades I possibly can, but outside of that I just know certain classes are very hard