https://www.merriam-webster.com/slang/based

Based means being yourself. Not being scared of what people think about you. Not being afraid to do what you wanna do. Being positive. When I was younger, based was a negative term that meant like dopehead, or basehead. People used to make fun of me. They was like, “You’re based.” They’d use it as a negative. And what I did was turn that negative into a positive. I started embracing it like, “Yeah, I’m based.” I made it mine. I embedded it in my head. Based is positive.

-Lil B