The end result is that the otaku and yankii have an almost inelastic demand for their favorite goods. They must consume, no matter the economic or personal financial situation. They may move to cheaper goods, but they will always be buying something. Otherwise they lose their identity. While normal consumers curb consumption in the light of falling wages, the marginal otaku and yankii keep buying. And that means the markets built around these subcultures are relatively stable in size.
So as the total market shrinks, the marginal groups — in their stability — are no longer minor segments but now form a respectable plurality in the market. In other words, if otaku or yankii all throw their support through a specific cultural item, that item will end up being the most supported within the wider market.
The clearest example of this is AKB48. With the letters AKB in their name, this group of girls was unequivocally marketed towards older males based in the Akihabara otaku culture. Compared to past mass market groups such as Speed, the girls are intentionally chosen and styled to look like elementary schoolgirls and lyrically address older men with direct sexual references. (See the “cat-eared brothel” video for “Heavy Rotation” and the unambiguous “love knows no age” lyrics for “Seifuku ga jama wo suru.”)
The mass idol group regularly has an “election” (sousenkyo) where fans try to vote their favorite girl to Number One. Buying certain AKB48 CD singles gives the fan a vote in the AKB48 election, which thus incentivizes otaku to buy multiple copies of the CD to increase their “political” power. The CD is thus no longer a means of listening to music but a way to influence the future of AKB48. This has created a legion of fans who buy dozens and hundreds of the same AKB48 CD or even 5500 copies. There are now doubts about that story’s authenticity but it basically was an exaggeration of an existing principle. Regardless, the marketing strategy of AKB48 does encourage the purchase of multiple goods, thus amplifying the buying power of nerds beyond their small numbers. This means as a consumer bloc, the AKB48 otaku fans can rival the non-otaku consumer base.