His enabler psychologist was giving him many drugs to deal with his already known bi/polar paranoia mental problems. His girlfriend and family finally sued Landy for malpractice to relinquish his legal control that Brian initially signed onto. I believe Landy lost his license and is now dead.
Brian became better in later years due to basic therapy and a couple of now accepted/recognized drugs for his condition. He can't sing a lick without going off key, but his improved mental health allows him to perform sometimes.
Here is a true expose on Brian Wilson's life:
https://nypost.com/2015/06/04/how-one-quack-doctor-almost-destroyed-brian-wilsons-career/
I always thought Mike Love was the better singer.
I tend to view Brian Wilson as being like Paul Simon.
Paul’s songs sound best when performed by someone else, like Art Garfunkel.
Brian’s songs sound best when performed by someone else, like his daughter Carnie Wilson, who does an amazing rendition of Good Vibrations with her sister as a part of Wilson Philips.