Fair enough but another factor is that Europe in the 1980s was the height of techno/rave culture and the demoscene fed off of that. Also, PCs didn't catch on so

Fair enough but another factor is that Europe in the 1980s was the height of techno/rave culture and the demoscene fed off of that. Also, PCs didn't catch on so fast and 8-bit machines (C-64s, Atari STs) and the Amiga stayed popular in Europe longer providing an accessible, colorful flower bed from which the demoscene bloomed. One more factor you shouldn't discount: In the U.S., drinking age is 21 and going for a weekend "rager" in another country over a long weekend isn't a thing here. Once you're ensconced in university a couple of years, staying up all night to code a bunch of spinning eye balls over a warp field holds less allure.