Ozzy Osbourne was fired from Black Sabbath in 1979 primarily due to his unreliability and excessive substance abuse issues, which were considered worse compared to other band members. The band was struggling with motivation and productivity in the studio, and Ozzy was often missing or too intoxicated to contribute effectively. Despite attempts to work with him, the rest of the band, especially Tony Iommi, decided that firing Ozzy was necessary to continue the band without breaking up. Ozzy himself felt betrayed because all members were using drugs and alcohol heavily, but he believed his level of substance abuse was similar to theirs. His dismissal followed a period of personal struggles including grief and dissatisfaction with the band's direction, and ultimately, the band felt they could not keep going with him in that condition, leading to his replacement by Ronnie James Dio.
