TIL that the Indian subcontinent used to be the largest economy of any region in the world between the 1st and 18th centuries

Sure. I'll add one guess that I've had for a long time as to one substantial factor in what helped start things get going in Europe relative to East Asia: moveable type. That drastically brought down the cost of written works, which acted as an enabler for subsequent social and technological changes, and happened towards the beginning of that "early divergence" period.

Why didn't it take off in East Asia?

East Asia had had block printing, even moveable type, for a long time before Europe. However, it did not use alphabetic systems of writing, and if you have thousands of logograms, the kind of practical "I have a small number of bins of identical characters" thing doesn't work nearly as well.

https://ca.pbslearningmedia.org/resource/moveable-type-story-of-china/moveable-type-story-of-china/

The Chinese first invented movable type during the Song Dynasty, but the complexity of the Chinese language made it cumbersome and not cost efficient.

https://en.wikipedia.org/wiki/Movable_type

A potential solution to the linguistic and cultural bottleneck that held back movable type in Korea for 200 years appeared in the early 15th century—a generation before Gutenberg would begin working on his own movable-type invention in Europe—when Sejong the Great devised a simplified alphabet of 24 characters (hangul) for use by the common people, which could have made the typecasting and compositing process more feasible. But Korea's cultural elite, "appalled at the idea of losing hanja, the badge of their elitism", stifled the adoption of the new alphabet.[20]

https://en.wikipedia.org/wiki/History_of_printing_in_East_Asia

A particular difficulty posed the logistical problems of handling the several thousand logographs whose command is required for full literacy in the Chinese language. It was faster to carve one woodblock per page than to composite a page from so many different types.[citation needed] However, if one was to use movable type for multitudes of the same document, the speed of printing would be relatively quicker.[20][better source needed]

Despite the appeal of moveable type, however, craftsmen soon decided that the semi-cursive and cursive script style of Japanese writings was better reproduced using woodblocks. By 1640 woodblocks were once again used for nearly all purposes.[67] After the 1640s, movable type printing declined, and books were mass-produced by conventional woodblock printing during most of the Edo period. It was after the 1870s, during the Meiji period, when Japan opened the country to the West and began to modernize, that this technique was used again

https://en.wikipedia.org/wiki/Printing_press#Gutenberg.27s_press

The invention of mechanical movable type printing led to a huge increase of printing activities across Europe within only a few decades. From a single print shop in Mainz, Germany, printing had spread to no less than around 270 cities in Central, Western and Eastern Europe by the end of the 15th century.[52] As early as 1480, there were printers active in 110 different places in Germany, Italy, France, Spain, the Netherlands, Belgium, Switzerland, England, Bohemia and Poland.[5] From that time on, it is assumed that "the printed book was in universal use in Europe".[5]

https://www.taiwan-panorama.com/Articles/Details?Guid=09433229-1971-44c8-a7fe-0193be415fbc&langId=3&CatId=11

In the 1970s, major newspapers in Europe and North America steadily entered the era of computer set printing, which was a great blow to traditional moveable type. Computer printing makes for faster entry, convenient editing and amending, and cleanliness, and saves manpower to boot.

So that would have been a technological window running from in the 1400s to something like the 1970s where it was cheaper to do production of written works in (alphabet-based) European languages than in (logogram-based) major East Asian languages.

EDIT: On another interesting note, the Soviets tried to promote an alphabet-based writing system for Chinese some time back.

https://en.wikipedia.org/wiki/Romanization_of_Chinese

Work towards designing Latinxua Sin Wenz began in Moscow as early as 1928, when the Soviet Scientific Research Institute on China sought to create a means through which the large Chinese population living in the Far East of the Soviet Union could be made literate, facilitating their further education.

From the very outset, it was intended that the Latinxua Sin Wenz system, once established, would supersede the Chinese characters.[16] The Latin alphabet was chosen over the Cyrillic alphabet because the former was thought to better serve their purposes

For a time, the system was very important in spreading literacy in northern China, and more than 300 publications, totaling 500,000 issues, were printed in Latinxua Sin Wenz.[16] Ultimately, promotion of the system ceased, because of its proposed target of superseding logographic Chinese characters altogether, which was deemed too radical:

In 1944 the latinization movement was officially curtailed in the communist-controlled areas [of China] on the pretext that there were insufficient trained cadres capable of teaching the system. It is more likely that, as the communists prepared to take power in a much wider territory, they had second thoughts about the rhetoric that surrounded the latinization movement; in order to obtain the maximum popular support, they withdrew support from a movement that deeply offended many supporters of the traditional writing system.[21]

For better or for worse will be the big question, especially since it's a major driver of climate change which may result in our extinction. In any event the world has been set on this path by the West so we will have to see how it plays out.