I’m not sure I’ve ever heard the term "mid fi" used without a being spoken in a deprecating tone of voice, as a means of asserting alleged "superiority".
Some assert it’s all about price -- that a component isn’t hi fi unless its price tag = X dollars or above.
Seems to me, hi fi is more about passion for connecting with music and willingness to experiment and learn how this may be accomplished, rather than price tag. Anyone with the requisite cash can fill a room with expensive gear. That, in and of itself, means little.