People with vulnerabilities often encounter people figuring those out and using them against them anyway. The more damaged a "2", the more often people will use them for help and dump them anyway. Or the more insecure and accomplished a "3", the more often people give backhanded compliments. People are often intentionally overly assertive and intrusive with "9"s. etc. Some people have ability at detecting weaknesses, while others just use a bulldozer technique where only the effective attempts are remembered by the person on the receiving end.
People figure this stuff out without Enneagram. The flip slide of that realization is that the one on the receiving end of the exploitation can also become expert at dodging and blocking those attempts. That's pretty much the experience of socializing throughout a lifetime in a nutshell.