Just read this book:

I remember, back in the day, I asked on IRC how to edit a file in Linux. Someone said vi. Little did I know that in chat someone said, the next question is how do I quit. I asked that exact question. Yes chat erupted.

I vaguely remember pressing Alt+F4 while trying to close vim in a terminal once. It did switch to me login prompt so I thought it worked.

Either by making it segfault or you don’t.

I got a whole software developer career going out of my attempts to exit vim.

For people who actually don’t know this, yet: Type :x.
This means “eXit, save any changes”

If you want to leave and discard your changes, type :q!
The :q means “Quit”, without any other instructions. This will warn you if you changed anything, adding ! means “force this command”.