Earlier quoted context omitted.
Agents are not just irrational, but also acting with limited information and limited computation. Amusingly, we have trouble getting a few hundred agents to act reasonably in RTS games, modeling 100's of millions of people for long periods of time is just shy of ludicrous.
But if you want to make pronouncements about how irrational agents actually act, a prerequisite to having any sort of scientific confidence. People on HN, not being economists and usually in a polemical mood when this topic comes up, generally strike me as thinking that "people are not entirely rational -> people are entirely irrational -> all possible theories of economics have now collapsed to the very simple thing…
100,000 agents is at least 1 million times easier than 100 million agents and you can't parallelize the problem very well due to speed of light propagation issues.
However, 100,000 agents is enough to do a lot of interesting research.