[lloeki]

The textual definition is slightly off: there are stupid people who cause no loss to anyone but themselves†. Think of stupid people doing stupid things you can see on gifs and youtube where their attempt at doing something ranges from extremely unlikely to completely impossible to achieve in a very obvious way combined with a strong likeliness that Things Go Wrong in a very immediate and physical way. So the value on the Y axis (loss to other) can be zero.

I posit a better definition of stupidity that includes a lack of foresight of "obvious"†† damaging consequences would be more appropriate. A corollary would be Einstein's possibly apocryphal definition of insanity.

† OK unless the guy lives in the most remote area, there will probably be emergency services involved.

†† What's obvious to one may not be obvious to another, and it's a common mistake to conflate lack of knowledge with lack of foresight. We should strive to be kind in our expectations, yet the fact remains that some people are profoundly stupid to the point of being survivally challenged.