Not all, some are industrious idiots.
(In his opus "On War", von Clausewitz classified soldiers into four separate categories:
Intelligent and lazy: these people should go into 'intelligence' or central high command, as they will work surprisingly hard and diligently to ensure that they do not have to get up at 2:30 in the morning to deal with unforeseen emergencies.
Intelligent and industrious: These people are field commanders, they react quickly and decisively to events and make usually sensible decisions based on what they know at the time, they are good tacticians.
Stupid and lazy: They are the foot soldiers, they will basically stay where you put them and do what they are told (if trained appropriately). They are too lazy to wander far, and too stupid to get into too much trouble on their own.
Stupid and industrious: These people are a nightmare and will cause no end of trouble. They won't stay where they are put, they will get into scrapes and tinker with things if not given something to do. They should be got rid of at the earliest available opportunity.)