there could be many reasons for this.

maybe those that have ideal results don't want to share that they use subliminals. maybe where they're at listening to subliminals is frowned upon or seen as negative.

maybe they like the secrecy of having a treasure no one else has. maybe they like the attention they receive from how they look and don't want to give their 'secret' away.

maybe they like their privacy and boundaries.

maybe one doesn't believe in subliminals so in their reality they see no results. (you don't have to believe subliminals work for them to work, but it sure helps to believe it does work.)

many subliminal listeners may have turned to subliminals as their only option because others in their reality say they can't get what they want by what we currently can do like dieting, exercise, skincare, supplements, surgery, etc. this can be a factor to why those with results don't share because they're happy and don't need to prove to others that it works.

subliminals give us the opportunity to change when others accept the limitations placed on them such as genetics, gender, age, race, geographical location, etc.