I'll just say, the old "I have no personal experience or understanding of X therefore it doesn't happen/isn't true" argument is not a strong one.
Also, it is not "impossible" to manipulate grown adults because it happens all the time, you just need to know what buttons to push and some people are more susceptible than others. Quinn did prey upon some people's vulnerabilities, gullibilities, and neediness for her own gains. This is undeniable fact. There is choice, but people like Quinn with means, motive, and ability can exploit a chink in a person's armor to make them choose the choice they want them to by making it the most appealing, and that's exactly what she did.
She played the role of the snake from the Garden of Eden, getting people to eat the apple she gave them.