Pilots will try and get to a safe 10,000ft ASAP
Gradual depressurization is just as bad, as oxygen masks only have enough oxygen for a limited amount of time. Once that runs out, passengers become sluggish and fall unconscious. Before that happens, though, the pilots -- wearing more advanced rubber oxygen masks -- will try to bring the plane to a safe and breathable altitude of 10,000ft.
Thanks to D.B. Cooper, planes are actually safer
At this point, you might be like: “But what about D.B. Cooper, didn’t he jump out of a plane and make off with $200k?" Well, good point. However, Cooper had forced the pilot to depressurize the cabin first, effectively unplugging the emergency exit before jumping out with a parachute. Since then, the FAA has forced airplane manufacturers to install something called the “Cooper Vane," which prevents the doors from opening while the aircraft is in flight.