[mftb]

...but then the difficulty of quitting Vim becomes a feature. Can't crash the system by exiting, if you can't exit (taps head meaningfully). /s

[goalieca]

Execute tmux using vim shell command. Kill -9 vim

/worth a shot?

[xorcist]

PID 1 is special and can not be killed with signal 9 for security reasons. See kill(2).

[mftb]

lol, the nuclear option. You don't mess around, but really, I think the answer is, never quit Vim.