Origin: 1970
The bottom line is, it's hard to tell when Americans truly began to focus on the term bottom line. We find an isolated early instance in 1967 from the San Francisco Examiner: "George Murphy and Ronald Reagan certainly qualified because they have gotten elected. I think that's the bottom line." In 1970 comes a financial attestation, in a book called Up the Organization: "All overheads should be brought down to the bottom line for bonus purposes on principles agreed to in advance." After that, bottom line became an established way of saying we were all business. "IBM has always been heavy on corporate paternalism," noted Newsweek in 1971. "Learson may well be willing to sacrifice some of that for those results on the bottom line." And in Harper's Bazaar that year: "His only interest is in the bottom line. He doesn't know or care about books or art or music or even his own wife--only about the bottom line."
The revolutionary, anti-authoritarian 1960s were over, and we were getting back to business. Today the bottom line is "the main theme, the final result, the end rather than the means." It can have any subject, even cigars, as in this 1973 question and answer: "Do you miss our Havana cigars?" "Well, in answer to that, and to get to the bottom line, I don't smoke."
We remain committed to bottom line in all sorts of contexts. In the Web pages of Heaven's Gate, whose members departed this world by poisoning themselves at Easter 1997 as the Hale-Bopp comet passed by, we find the heading "Do's Intro: Purpose--Belief: What Our Purpose Is--The Simple 'Bottom Line.'"