Why? And where do your figures/estimate come from?

…Here's a small selection of what actually happened in the pre-internet/computer era (it's all pretty remarkable and we could do it again if we had to):

• Humanity got through many tens of thousands of years of its existence and into the 1980s without the internet and (mostly without) modern computers and somehow not only managed without them but it thrived and multiplied.

• Even before electrification and the international telegraph across the Atlantic, trade was alive and well between nations (for instance, trade in cotton from the Southern US to Manchester UK).

• Moreover, in ancient times trade between nations was both effective and remarkably well organized (given that even the telephone was still 2000 years away). One only has to look at the trade routes of Ancient Greece and the Roman Empire to realize how sophisticated that arrangement was: https://vividmaps.com/trade-routes-of-roman-empire/. Furthermore, there were many other trade routes throughout history, The Silk Road for instance.

• At the beginning of WWII the US was almost completely unprepared for war. Between 1942 and 1945 the US embarked on an industrial ramp-up in production that has never been equalled. That increase was truly phenomenal: https://prospect.org/health/way-won-america-s-economic-break.... All that occurred without either the internet or modern computers.

• As US Secretary of War Henry Stimson said in 1940 "If you are going to try to go to war, or to prepare for war, in a capitalist country, you have got to let business make money out of the process or business won't work.". That actually happened and the results were not only remarkable but truly phenomenal. It's not the internet that drives the world but money!

• There are a few notable exceptions to that rule (but nevertheless commerce was unknowingly and inextricably implicated), and that was the Government-run Manhattan Project and the development of the Atomic Bomb. War has always driven scientific development but what happened between 1942 and 1945 was truly phenomenal and still has never been equalled in both the speed of scientific development and its practical application. It is all the more remarkable that from its outset the Manhattan Project was planned, organized and brought to fruition in complete secrecy—and, of course, this secrecy also extended to all the scientific and engineering research. Not only was there no internet, but mandatory secrecy meant that discussing the project on the telephone was impossible—even speaking to anyone with the exception of security-cleared colleagues in one's own area of specialty was not only problematic but also a major breach of security.

• Another exception was the phenomenal strategic planning and organization behind D-Day—the invasion of Normandy during WWII. This was the biggest and most complex invasion of its kind in all history, nothing like it has ever happened before or since. Again, this remarkable feat was accomplished behind an enormous cloak of secrecy.

• It wasn't only the US that had a phenomenal increase in production in WWII, so did every country engaged in the war: https://en.wikipedia.org/wiki/Military_production_during_Wor.... For example, in 1939 the world produced ≈38,000 aircraft per year, by 1945 that figure was not only phenomenal but had reached a staggering number in excess of 0.8 million aircraft per year! That's an increase of ≈2105%: https://en.wikipedia.org/wiki/World_War_II_aircraft_producti....

• After WWII the US post-war economy growth was also phenomenal: http://www.let.rug.nl/usa/outlines/history-1994/postwar-amer.... Other countries also had phenomenal economic growth after the War.

• It wasn't only economic growth throughout most of history that managed without the internet or modern computers, science and mathematics did too. Essentially, all mainstream mathematics and mathematical theories up until the 1980s were done without the help of even electronic communications let alone the internet. Moreover, mainstream science from ancient times to Dalton's scientific method; to Enlightenment science, Lavoisier et all; to 19th Century science—thermodynamics: Clausius, JW Gibbs, Boltzmann; electrical theory: Faraday, Maxwell—Maxwell's equations; through to 20th Century science: Quantum Mechanics: Planck, Bohr, Einstein, Dirac, et al right through to QFT, QED and even the Standard Model of Particle Physics —still our most current model—all happened without the internet—that's right, every damn iota of it!

• And lastly, culture: essentially all the great cultural canons, music, art and literature, were produced without the need of the internet or computers, or for that matter, even without other forms of modern electronic communications.

No doubt, if the internet ceased tomorrow there would be widespread disruption and it would force everyone to adapt quickly (especially after it was realized those technologies weren't going to return—keep in mind that this would very likely be the scenario after a nuclear conflagration/war).

In my opinion, the single biggest problem for post-internet, post-computers times would be re-educating the generation that has grown up with them ever present and has never known or experienced a world without them. (Moreover, the disappearance of computers and internet would likely be a very serious social problem (at least in the short term), the reason being that with their introduction it was the first time in history that humans have experienced truly addictive work tools and withdrawal would be difficult. It would be especially problematic for those who've grown up with them from birth.)

Please note, I'm not suggesting for an instant that this scenario is desirable or that a pre-internet, pre-modern computers world would be sustainable into the distant future, so please don't accuse me of being a Luddite. After all, my bread and butter has always depended on technology—and I've always been a born technophile. My views here are based on the fact that I grew up before the internet so I've experienced both worldviews.