I lived in apartments for a long time then moved into a house. I thought my cat who had never seen stairs would take some adjusting. Nope, he look up them, wiggled his butt, then ran full tilt to the top. Ran full tilt down them too.

One of our cats has arthritis and before we got her treatment she didn’t like them, but she’s perfectly happy now.

Carpetedness may make a big difference in this case.

I've had cats that love stairs. They'd play and slide down them on purpose.

Pretty sure cats love climbing things, and stairs are no different.

so you probably never had cats that run up and down stairs 10 times at 6am.