Same reason that the people who pick and remain with NPD’s are very slow to change as well …
Because EVERY human has an unconscious drive to stay near the familiar (preserve homeostasis) … and most people won’t change patterns for which they get rewarded.
If people who are plagued with deferral of assertion keep picking, dating and sleeping with them, why in the world would they want to change … it seems to be working!!
https://new.quora.com/What-makes-describing-narcissistic-abuse-to-non-narcissists-so-difficult-12