What is something really stupid you purchased that turned out far better than expected?
I bought a piece of 1.5 inch stiff foam to try to fix a sag in a bed. It didn't work but having that thick piece of solid foam around has been a life saver.
Need something flat to put a laptop on? Throw it on the foam. Going to be doing something that requires you to be on your knees for a while? Get the foam!
It went from stupid purchase to something I'd gladly replace if it broke.
I wanted to buy a small silicone spatula for specific uses, but they were only sold in a set of 5. I was like what am I going to do with that many spatulas but they're super useful and are amazing at scraping and I love having extras so I don't have to constantly wash them.