These days if you get in to NYT or Amazon top list, you are talking about windfall in range of $10M. For books like Fifty Shades of Grey this was at $100M for the author. So writing books these days is not poor author trying to getting by but a very very serious business. It's as serious as Series C startup with actual office, roadmap, business plan, marketing plan and even full time employees who would do research, citation collection, word smithing, editing etc for you. People like Tim Ferris and Malcolm Gladwell have made this to an art form and are some of the most successful founders for this type of business. The way they work is by taking couple of known data points in academia and expand it on to 400 page book dishing it out as fundamental insights that everyone is missing out on. Such books are rife with repetitions, personal stories, cherry picked anecdotes, raising underdogs and putting down others that evoke emotions but at the same time tuck away the other side of the story that would have made them more balanced and boring.
I wouldn't be surprised if Taleb has made more money from his books then his hedge fund career and accordingly he might be more aggressive to protect his image as dispenser of great counter-intuitive insights. His assertions in these sets of tweets are obviously overblown. IQ testing is known to be very faulty measure for intelligence but at the same time lot of rebellious personalities including Einstein, Bill Gates, Lady Gaga etc have had high (> 150) IQ. No one would call them people yearning to be obedient salaried drones.