Just done a quick calculation.
In the Awake! Magazine dated May 22nd 1969 page 15 they said:
"If you are a young person, you also need to face the fact that you will never grow old in this present system of things. Why not? Because all the evidence in fulfillment of Bible prophecy indicates that this corrupt system is due to end in a few years. Of the generation that observed the beginning of the "last days" in 1914, Jesus foretold: "This generation will by no means pass away until all these things occur."-Matt. 24:34. Therefore, as a young person, you will never fulfill any career that this system offers. If you are in highschool and thinking about a college education, it means at least four, perhaps even six or eight more years to graduate into a specialized career. But where will this system of things be by that time? It will be well on the way toward its finish, if not actually gone!" Awake! 1969 May 22 p.15
If you were 17yo in 1969, you'd be 65 years old now. That means you not only would have completed your college course, but you would have had you whole career and be retiring this year (in the UK at least). Ample time to start full time pioneering while having a comfortable nest egg, family and nice home.
Watchtower shot themselves in the foot there. Just think of all those lovely pound notes that could have been flittering their way to bethel since 1969 from educated, well paid members.