Does " they will overestimate" refer to "the (some people) will overestimate"?
Context:
Both researchers were in the lab wearing highly specialized equipment and under ideal conditions. They also had to obtain and follow a stringent set of international human-subject testing rules to conduct the demonstration. "I think some people will be unnerved by this because they will overestimate the technology," Prat said. "There's no possible way the technology that we have could be used on a person unknowingly or without their willing participation."
The point is that some people will be afraid of this because they will think that the scientists can do much more with this than they actually can. The people will think that the scientists will be able to use a computer to take control of someone's actions against the persons will, which is not something the scientists can actually do.