In simple words a formula one engine has 900 hp. The brake system can develop 3000 hp.
the 700 hp's are only a medium value of the brake from 330 to 60. but in the first istants of the brake (for example from 330 to 300) the car weights not 600 but about 2200 kilos (due to downforce) but has the same inertia.
This cause two effects : more brake force from the road (due to downforce) and a drammaticaly decrease of the time of braking (due to the same inertia). This explain why a formula one brake system develop 3000 horse power.