Not only that, but we have multiple on differing levels of the idiot scale depending on the topic at hand. The biggest idiots I've encountered are brilliant people outside their knowledge domain.

The other way around I hope ;)

*The biggest idiots I've encountered are brilliant people within their knowledge domain.

Exhibit A: me writing ;p

Don’t worry :) I read it as “The biggest idiots I've encountered are brilliant people (who are [idiots when they are]) outside their knowledge domain.”

  >  we have multiple on differing levels of the idiot scale depending on the topic at hand

or even depending on the time of day, or current stress/work levels

alot of things can affect the idiot scale...

That's very narrow way of thinking ... I believe myself to be idiot in multiple different ways which can have multiple dimensions with multiple different scales.

And the real problem is that it is only a really small set of things one person can have even mediocre competence during one lifetime, whereas the space of things where you can be completely idiot is infinite. So, as a very good approximation, we all are complete idiots.