The dispiriting effect of the lack of opportunity is a definite cause IMO.
Not to deny many other factors such as the lack of fathers, the useless schools, exposure to the feminized product of the media...
My point was that the opportunity is still there, the boys just aren’t doing it, the bicycles, parts, engines, wheels, switched, wire, junkyards, things they want and could build or assemble, are all there or waiting to be built, so something else has changed.