what they were not was a university baby boomer?

主句是主系表结构，即：
主语(从句) What they were not
系动词 was
表语 university-... baby-boomers

后面则是一个定语从句 who... them，用来修饰主句的表语。
定语从句则是主谓宾结构，其中 who 是关系代词且在从句中做 主语，谓语是 believe，后面是两个用 and 并列的宾语(从句)。
第一个宾语从句是 all events ... controlled，第二个宾语从句则是 that everything ... on them。
第二个宾语从句中还含有一个定语从句即
I did，它修饰从句主语 everything

扩展阅读：journalism ... what were they doing ... what fools they were ... virtually ... the name of love ... in the first photo ... what they were about ... a term of contempt ... the number of ...