I bought a Blackberry Playbook when it went on sale. Did not really need a tablet but thought it would be cool, it was also my first smart device so I liked the idea of a portable device with wifi to use around the house. Downside is it lacked apps, and the wifi on it was really screwy. It would just die, and the only way to get it going again was to reload the OS. So other than the first couple months it sat in a drawer until the battery died completely. It locked up and I could not turn it off so I just let it die. Pretty sure even the BMS portion was locked up so it literally killed the battery flat.
I probably have other stuff I rarely use, but this one is probably the biggest one where it was really a waste. Thankfully I had not paid all that much though, like $200-$300.