There are 5 major frontier labs competing in the US alone with serious capital. Perhaps only 2 of them are are truly in contention for the top spot, but it's highly competitive. Then throw in the handful of very serious sub-frontier open weights labs, who are creating huge price competition for the frontier labs, and I have no idea how you can come to this conclusion.

Cloud is no different: 3 major cloud vendors, with 1 clear leader...and now a long tail of tier 2s and neoclouds that are also investing incredible sums to compete.

Where is the pre-structured duopoly? Where is the profit moating?

There are 2 US frontier AI labs. The others aren’t competing at the frontier hence no concern for national security or moating. The moat is 1 main, 1 backup/pusher.

You can’t build a fighter jet in your garage.