nyrath , 
Rocket packs have drawbacks.
Jet packs carry chemical fuel but uses atmospheric oxidizer. About 10 minutes before the fuel is used up.
Rocket packs carry both fuel and oxidizer. About 30 SECONDS before the fuel is gone.
Hard to increase duration, short of nuclear energy.
Users typically fly with rocket packs at an altitude too low to use a parachute (below 30 meters) but too high to survive the fall (above 9 meters)