I remember one time I installed a lot of themes for my session and I broke something and the themes changed my icon files forever and I had to reinstall Ubuntu!!
Should I just stick to changing my wallpaper and other small tweaks? I don’t really like using vanilla Ubuntu anymore, it doesn’t feel like me. Thank you very much!!
Have backups. Use something like Veeam Endpoint or a similar software that will image the entire system in a bootable state, and schedule it daily with incremental storage.
Every day stuff could potentially break something, updates out of your control could break something, hardware failures happen, etc…