Bobby qualifies technically as Jewish, since his mother was descended from Jews, but she was not religiously observant in any way and did not provide a Jewish upbringing for him.
Everyone following this thread needs to read an excellent article from a couple decades ago
https://www.theatlantic.com/magazine/archive/2002/12/bobby-fischer-s-pathetic-endgame/302634/
I think the article provides a basis for saying that Bobby suffered from paranoid delusions as he got older.
No Fischer was not crazy. He connected with the world on his own terms and refused to be manipulated or pushed around. He was his own man. He did not cash in when he clearly could have had the good life. He saw the world through the eyes of a self made world champion. He bowed to no one. He was eccentric and ego driven. He had no soul mate and could not form any relationship of lasting value to him. He was brilliant and yet flawed. All near him found him a pain yet many still sought his company. He rejected the friendship of many, only the exasperated left his company. Most left him alone. He deserves his place in chess history, he deserves nothing but scorn for his derision of the world and his hatred of the USA and of the Jews who he regarded as snakes. What a shame.
Famously, Bobby was a an antisemetic Jew, which is weird