Yep. I had a laptop that came with Windows 8 on it.

I booted it once into Windows to change UEFI settings and then put Lubuntu on it.

Well, a friend had a Windows question for me when I was away at a conference. No problem!
I booted my laptop into Win8, looked up how to do the thing, and told her. I went to bed.

I woke up to find that my system had:

1) autoupdated to Windows 10
2) fucked the bootloader so I couldn't boot into Linux any more.

This is on top of the fact that Windows updates take about a year to complete and reenable
a bunch of crap that I keep disabling ("Windows Media x").