lol - don't worry, we all do stupid things.
Take me for example...
From November to mid January (the most recent one), I thought my Rocksim was broken. All sims were resulting in gross underestimation of altitudes, to the extent that it thought a Cirrus on a J350 would only do 6600 feet. This of course is absurd, so I started looking around for the cause.
After 2 and a half months, I realize air pressure is set to 55" Hg.
DOH!!!
That has to be one of the stupider (though probably not the stupidest) things I've ever done.