I did last year. Sold a really nice 78 RD400, thinking I wanted a bigger, more powerful bike. Ended up buying an 85 Suzuki GS1150. Long story short, the Suzuki turned out to be a huge POS. It didn't have the correct engine, the engine it did have had a bunch of mis-matched parts, wrong year carbs, etc. Ended up unloading it as soon as I got a title in my name from the DMV. I owned it a total of about 3 weeks, and every day I had to look at it in the garage I would think to myself, 'what have I done?'
I lost a bunch of money on it, but I didn't care at that point. I just wanted it out of my garage!
I want my RD back!