It’s a picture of a parabola if someone put the y axis at the dotted line not the origin. If you want to bargain with people - and this fictional conversation is a negotiation - then don’t anchor the people on bad values.
See the quote below.
That said, while I didn’t think it was a confusing drawing, I now wish he’d drawn the rest of the parabola, because it would’ve prevented this whole conversation.
> EM: Woah! That’s no good. Wait, if we turn the carefulness knob down, does that mean that we can go even faster?
> TL: If we did that, we’d just be YOLO’ing our changes, not doing validation. Which means we’d increase the probability of incidents significantly, which end up taking a lot of time to deal with. I don’t think we’d actually end up delivering any faster if we chose to be less careful than we normally are.
If you centered it on the y axis, that would mean your carefulness scale goes from -5 to 5, and that's just confusing.