It's called "suspension of disbelief". People believe this stuff because they mistakenly believe that their percieved physical shortcomings are the source of their unhappiness...and we can thank the media for perpetuating that myth, for feeding our collective insecurity..
"I have a dream that my four little children will one day live in a world where they are judged by the content of their character and not by the color of their skin." -Martin Luther King, Jr. (probably slightly misquoted... :))
That quote speaks to racism, but can be applied to the selling of supposed "cures" for what we believe ails us...