Diminishing returns can suddenly materialize and bite you in the ass - just look at EV's now. Same with audio equipment which is always subject to unforeseen technological displacement. You hear lots of cheerleaders now touting the demise of class A and AB amps in the face of GaNFET's. They may suddenly gain enough momentum to cause a feeling of diminishing returns for everybody in possession of outmoded technology or what is perceived to be outmoded.