By "substance abuse" I assume you're referring to regular in-office and at-home drinking and cigarette smoking practiced by the main characters. In his book The Alcoholic Republic, William Rorabaugh identifies that total alcohol consumption increased markedly throughout the 1960s and into the 1970s (he stops at 1975, about where the series itself might conclude). We can point to a few influences: rising postwar affluence and advertising of beer and liquor, a lack of understanding about the physical dangers of excessive drinking, and of course the corporate world's masculine environment, most of which in American history have featured alcohol. Cigarettes were generally understood to be dangerous after the 1950s, but lots of people still smoked. Remember that alcohol and tobacco enjoyed a privileged status in American society at this point, removed from the category of deviant drugs like heroin and marijuana (for a variety of reasons worth their own post!)

I'm less well-versed on the chauvinism aspect, but Lizabeth Cohen points out that much of the postwar affluence was enjoyed by white, well-to-do men. The G.I. bill and government-backed home loans were largely distributed through extant discriminatory private sector channels. Single women were typically denied access to credit cards until the early 1970s, and in fact retained no credit standing when divorced, separated, or widowed. It is not a stretch to imagine this systemic attitude filtered up into the mostly single-sex corporate world of the 1960s. See her A Consumer's Republic.