AIs deviate from their intended programming, in ways that are dangerous for humans. And it's not thousands of years away, it's away just as much as a self-driving car crashing into a group of people to avoid a dog crossing the street.

But that's a very different kind of issue than AI taking over the world and killing or enslaving all humans.

EDIT:

To expand: all technologies introduce safety issues.
Once we got fire some people got burnt. This doesn't imply that UFFire (Unfriendly Fire) is the most pressing existential risk for humanity and we must devote huge amount of resources to prevent it and never use fire until we have proved that it will not turn "unfriendly".