There is a really long, windy, steep hill near me called Succombs Hill, which has a 25% gradient. I once got stuck behind a cyclist who decided to cycle up it. It’s a narrow road with not much chance of over taking on it. So the traffic was forced to go up doing about 5mph. I stalled in the steepest bit, which was a right pain as my hill starts were shit. I take the longer flatter route now, and avoid that hill.
I guess they saw it as challenge.
Here is someone cycling down it.