Thats such a troupe.
You absolutely don't have to have low self esteem to wind up dating a narcissist.
Not if they slow boil you like a frog being warmed up in a pan. Especially so if you have never encountered their kind before or don't know about narcissists.
This is exaclt the reason there's so much victim blaming around. The suggestion that the fault is somehow with the abused because of some sort of flaw in their own personality.
It's human nature to think the person who's been nice to us for the first 6 months or so, IS nice. And to assume we've simply misunderstood them if they start to change.
It's a studied phenomenon that we are more likely to attribute positive traits to people we see on a regular basis.
As for poor boundaries.. again that's not necessary from the start either. Because narcissists erode boundaries. They are experts at finding weak spots.
Unless you can spot what they are early on qnd get away, you can have the healthiest self esteem qnd best boundaries in the world but with enough time and proximity, they'll wear them down. They have a multitude of techniques to accomplish it.