Furthermore the belief that I, a smart and well informed person, am immune to manipulation is a vulnerability those seeking to manipulate you can exploit.

While I agree in general, the nuance is that certain people are in fact more susceptible than others.

Hypnotists bring up a bunch of people on stage just to find the one most susceptible to their tricks.

On the other hand, well designed manipulation like YouTube’s recommended videos can keep even the least ignorant people enthralled in videos.

You're right of course. We're all susceptible. I still maintain that ignorance is the dry kindling to misinformation's fire, while a well-educated populace is more like damp log.

While I agree that everyone can be manipulated and we should never consider us immune to manipulation, I would still argue that certain groups of people are more easily manipulated.

You can make a poker player believe anything but I’m not surprised that some people can’t break even.