Six or so years ago I was using a (fairly cheap) Virtual Private Server as a dev/testing box for a pet project of mine.
The VPS company was bought by a larger company, and prices were to double on the next billing period. I hastily chose a new provider without doing any research. I paid for 3 months of service in advance, got the container set up the way I like, migrated all of my data over, and was up and running.
2 months in the new provider vanished, along with all of my data. I wasn't very concerned about the months worth of money I had lost by not getting the 3 months I had paid for, I think it was only about $15. "Okay," I thought. I'll just pull my data out of my nightly backups and move on. It turns out I forgot to adjust my local cron script that pulled the data over rsync to the new IP address. My backups had not been pulled in over 2 months.
Luckily it wasn't very important, as it didn't make me any month and was mostly just for fun. I ended up starting over from scratch and ended up with a better system anyway.
I learned my lesson, though.