Have you ever done anything stupid in your writerly/artistic/musical efforts? I have for sure. When I had the flu I kept forcing myself out of bed to edit my first draft. With body temp going up and down, I was determined to fix what I thought to be horrible grammar mistakes, only to spend many months afterwards fixing the fixes. Oh how I regret that mistake! Another one was sending out my manuscript before it was ready. I thought it was ready, but know now to put a manuscript aside and work on something else for a while. Doing so gives you the needed space and gives you perspective. Always, always wait before querying.
But in the end, every stupid mistake was worth it, really. With humility, we can all appreciate the stupid things because they help us to grow, they give us depth, they make the ending so much sweeter.
So, what are the stupid things you've done in your chosen craft?