What's the biggest mistake that stock market investors make?

I love stock market and have been invetsor since 2006 . I have traded in options and have various experiences - good , bad in stock market . I believe biggest mistake people make in stock markets is not investing enough time or money to educate themselves . They would see 10s of youtube channels , consult friends and take opinions of people who are not experts and then finally take their own decision unsystematically . That is the reason SEBI is discouraging people to trade in Future Options especially Options because Options are sophisticated instruments which if nt learnt well can lead to big losses . Therefore my mantra always is to educate yourself -- invest time and find a good teacher to educate yourself . read less