This is a topic people have been at a loss to reasonably answer for
a long time. It could even have something to do with the doctrine of
dispensationism. People are then no longer under the dispensation of
grace, but are back under the Law of Moses ... Which is another true,
deep, and much-disputed rabbit hole! 
   My final take on this is that It seems quite likely that since the
AC’s mark connects a person to this Artificial Intelligence system,
that this system will control them.
  The Bill Gates type People, who are literally indwelt by fallen
angels, are today creating this AI system. Through these indwelt
people, Satan could/ will indwell and control all of lost humanity.
  So, once a person takes the mark, they are no longer able to repent.
Lewis B