Sex appeal is the destiny of female celebrities

Female celebrities must be spotlighted for their looks to gain popularity, but for those who rely on that, interest drops sharply once they enter their mid-30s. Even if they maintain their beauty, interest fades simply because of their age.
This happens because, even if people know they won't be with them, the instinct for species preservation subconsciously begins to distance them.
For male and female idols, this mechanism of sex appeal is deeply embedded and processed through the metrics of popularity and fandom.
Once they pass 30, they must appeal through non-visual skills, such as acting or singing ability, to maintain a presence; the era of receiving attention just by existing eventually passes.