How do you figure 120mph? It's ~1kg and I would guess has a higher surface area relative to mass than a person whose terminal velocity is about 120mph.
In any event, it takes a person 8s to get close to terminal velocity — that's a drop of 300m or so.
The energy involved is certainly non trivial but energy is not the whole story. The densest, heaviest pieces will be the battery and motors.
The energy we are talking about is not insignificant. I'm actually in favor of allowing people to fly drones with as little restriction as possible but let's not pretend there aren't some risks.