You can't make a bad speaker good, but also: people spend lots on gear, but forget the room. The room can break a good speaker easily.

Also... 'good' is something you first need to agree on when talking with people. Some people like to have 'distorted' playback (compared to the original), because they "like" that better. That is the moment retailers can sell objectively worse but overpriced stuff.

Genelecs for instance are very detailed, neutral etc (there is a reason you see them everywhere in professional settings), but consumers don't necessarily have an appetite for 'objectivity'.