Because 7 8 9.
BECAUSE SEVEN ATE NINE *drops mic*
It ran out of cache.
Why did the number 6 cry? Because 7 8 9. (7 ate 9)
Hey Microsoft, why is there no Windows 9? You've given us 7 and 8, and now you're skipping straight to 10?" "Well, to be completely honest, 7 8 9."