Brain Scanning vs. Self-Rated Brain Activity

On Twitter this week I joked that neuroscientists could save money on brain scanners by just asking people how active their brains are.Why do we spend so much on neuroimaging and then rely on self-report measures of the other variables of interest? Why not self-report brain activity, how active is your amygdala 1-10? https://t.co/ph3A2Uc6zc— Neuroskeptic (@Neuro_Skeptic) November 6, 2019
However, it turns out that there has already been a study that actually asked people to do this,