Has anyone attended any kind of Hidden job markets seminars

On social media I get multiple ads regarding the hidden job market or career hack. In addition people say they got 100% hike or promotion in the company without switching.

Has anyone attended any kind of seminar or watched the seminar by paying 100, 1k ,2k...

I want to check a few facts that are real or not... What kind of things they show which is not followed by regular job searches ?