Priyanka turned 30 in July 2012. Her best career phase happened with Barfi! which came out in September 2012. After that she had Mary Kom (2014) which was the biggest female lead opening, and Bajirao Mastani (2015) which got her several awards and tonnes of acclaim.
Aishwarya Rai turned 30 in 2003. She became a huge international star by 2004. Even today she is one of the biggest stars and has had several hit films between 2003 and today.
Kajol turned 30 in 2004. She's had arguably her best work post that. Fanaa, U Me Aur Hum, We Are Family, My Name Is Khan are up there with her best work.
Madhuri Dixit turned 30 in May 1997. In October of that year she had a massive hit and won a lot of awards for Dil To Pagal Hai. Today even at 50, she is a worldwide superstar, people from all over the world watch her videos and adore her and appreciate her talent.
I could go on listing 50 other names, but your theory is already proven to be a false flag so bye.
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