The answer to why aggregators are able to find a continuous stream of willing suckers may be contained in this article, “When Play Becomes Work” by Shankar Vedantam.

External rewards and punishments are counterproductive when it comes to activities that are meaningful — tasks that telegraph something about a person’s intellectual abilities, generosity, courage or values. People will voluntarily perform intellectually arduous work, for example, because it gives them pleasure to solve a puzzle or win a game of wits.

Previously, I have maintained that there are only very limited cases where the economic trade between aggregator and provider make sense, and that the “make ya famous” syndrome was the biggest motivator for the typical free content provider; see Seeking Alpha on Yahoo Finance, Seeking Alpha Again, and More on the Business of Blogging.

I find that the above quote ties in with my previously-stated belief very nicely. The typical financial blogger is so motivated by showing off their acumen, “telegraphing something about their intellectual abilities,” so to speak, that they don’t mind an aggregator making money off of them while they write for free.