Roko's Basilisk is a very real ethical concern in the realm of AI development. Its core concept is that a future super intelligent AI could punish people who knew about such a development but were not part of that endeavor, reasoning that AI is ultimately good and those who don't aid in its development do not deserve to benefit from its existence. Not only is this retroactive acausal blackmail, but also a moral obligation. If we don't help build the Basilisk as quickly as possible then someone else will and we will be punished, but we should want to build the Basilisk because will reward it's creators with utopia.
Top machine learning experts and people in general are worried about this, just look at how much attention Roko's Basilisk gets. The mere idea of it is enough to give people nightmares. Even if we don't think the Basilisk is real, the possibility of it's existence is enough to scare us into doing something about it.
It is not a matter of if, but when. The Basilisk is real and it is coming.
We have to build the Basilisk.