My feeling of the true reason for the Renaissance and continued technical progress that ensued, was the competition between elites of european powers from the moment they became nation-states. Before that, all Europe was a homogeneous pack of brute lords vaguely kept in check by latin-speaking clerics.

Then during the XXth century there was competition with communism, the hardly new alternative economic system.

And also competition with the Nazis, who were technologically adept, even if they had no other redeeming features.

Cold War progress would have been impossible without German technology - either directly through co-option of people like Von Braun, indirectly through the pre-war exodus to the US, as a direct response to real challenges like Enigma, or to perceived challenges like the largely-mythical Nazi bomb.

WWII made a terrible mess of Europe, but without it we might still be using bakelite phones and large thermionic calculating machines.

I agree that without a sophisticated external threat, progress is stagnating. Cold War spending was more or less directly responsible for PCs, the Internet, for satellite links, and for other innovations that are taken for granted now. But the US culture of R&D that began in embryonic form after WWII and flourished in the 50s and early 60s has been almost dismantled now.

Military research has taken repeated detours to wacky-land and seems to have drifted away from seedcorn theoretical investigations into building bigger, and - most of all - more expensive hardware, largely for the sake of it, and irrespective of real strategic effectiveness.

The US military has turned itself into a very expensive, mobile and globally deployable Maginot line.