1 : magnets are often powered for a very, very, VERY long time. hard rock magnets lose 10% in 10 years (?), so they say, but if this is the case, I wonder how accurate this estimation is. This also depends on what material it is too, as higher quality magnets can be operable for dozens of decades. A refrigerator magnet will wear out before a stone magnet.



2 : magnets exert force on surfaces of steel and other materials. The force can be astronomical at times, to the point cat scans(?) can be fatal with metal objects, with them ripped out of the body. Larger, industrial magnets are labeled with hazard warnings, as having a pocket knife in your hand within to close a distance can have an amputation hazard, and your hand being pinched between steel and magnets will rip them off.



3 : Engineering exists to redirect, and funnel energy off of otherwise "static" energy sources. There are turbines, and other machines which have been developed to take in energy from x force, and turn it into energy



4 : I've seen literally no element in the rules of physics which would make the combination of point 1-3 into a powerful, long lasting generator with 0 immanence costs (maybe an occasional oiling?) and very clean (unlike radiation powered reactors).



So, unless you would like to redirect me to something which explains why exactly a magnet driven motor could not exist, I see no reason why it is impossible to develop. The force exerted from a magnet, which is constant, and nearly limitless, unless you have evidence to say otherwise, could be engineered into a means to drive a turbine or other object rather easily.