"How did we get so disempowered?"

Because we are trained by the society not to trust ourselves, not to believe that we are capable to make sound decisions. We are trained to give our power first to our parents, then to our teachers, then to our employers, to our doctors, therapists and other professionals, to political, business and religious leaders etc., etc. There is always someone whom we are supposed to listen to because they "know better". Their "expertise" or their title or their societal position gives them the authority to tell everyone else what to do and we buy that.

This is NOT to say that there is no legitimate expertise or legitimate positions in which people can have more knowledge and experience than others and thus it's a good idea to pay attention to what they say. But we give our power away when we start believing that their knowledge is ABSOLUTE gospel and start blindly accepting everything they say without any scrutiny.

We give our power away the moment we decide not to use our critical thinking, to dismiss our intuition and to overlook some obvious realities that contradict what the people in powerful positions are preaching. We tend to do that because it's, actually, much easier to give our power away than to use it. Using our power implies embracing the freedom to make our independent choices, but freedom always comes with responsibility. Once we accept that we have the freedom to make a choice, we would have no choice but to accept that we are fully responsible for the choices we make. And that is something that most people are unwilling to do. Hence it's much easier to stay dependent on someone and to suffer from the lack of personal power than to liberate ourselves.